EP4251715A1

EP4251715A1 - Method for hydrodesulfurization in the presence of a catalyst on a mesoporous-macroporous substrate

Info

Publication number: EP4251715A1
Application number: EP21807139.7A
Authority: EP
Inventors: Philibert Leflaive; Etienne Girard; Antoine Fecant
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 2020-11-27
Filing date: 2021-11-18
Publication date: 2023-10-04
Also published as: AU2021387713A1; FR3116829B1; KR20230115292A; MX2023005253A; US20230415131A1; WO2022112078A1; CN116547070A; FR3116829A1; JP2023550820A

Abstract

Disclosed is a method for the hydrodesulfurization of an olefinic gasoline cut containing sulfur, wherein said gasoline cut, hydrogen and a catalyst are brought into contact, said catalyst comprising a group VIB metal, a group VIII metal and a mesoporous and macroporous alumina substrate having a bimodal mesopore distribution and wherein: - the volume of mesopores having a diameter greater than or equal to 2 nm and less than 18 nm corresponds to between 10 and 30% by volume of the total pore volume of said substrate; - the volume of mesopores having a diameter greater than or equal to 18 nm and less than 50 nm corresponds to between 30 and 50% by volume of the total pore volume of said substrate; - the volume of macropores having a diameter greater than or equal to 50 nm and less than 8000 nm corresponds to between 30 and 50% by volume of the total pore volume of said substrate.

Description

HYDRODESULPHURIZATION PROCESS IN THE PRESENCE OF A CATALYST ON

MESO-MACROPOROUS SUPPORT

Technical area

The present invention relates to the field of the hydrotreating of gasoline cuts, in particular gasoline cuts from fluidized bed catalytic cracking units. More particularly, the present invention relates to the use of a catalyst in a process for the hydrodesulfurization of an olefinic gasoline cut containing sulfur, such as gasolines resulting from catalytic cracking, for which it is sought to reduce the content of compounds sulfur, without hydrogenating olefins and aromatics.

State of the art

Petroleum refining and petrochemicals are now subject to new constraints. Indeed, all countries are gradually adopting strict sulfur specifications, the objective being to achieve, for example, 10 ppm (weight) of sulfur in commercial gasoline in Europe and Japan. The problem of reducing sulfur content essentially focuses on gasolines obtained by cracking, whether catalytic (FCC Fluid Catalytic Cracking according to Anglo-Saxon terminology) or non-catalytic (coking, visbreaking, steam cracking), the main precursors of sulfur in gasoline pools.

A solution, well known to those skilled in the art, for reducing the sulfur content consists in carrying out a hydrotreatment (or hydrodesulphurization) of the hydrocarbon cuts (and in particular gasolines from catalytic cracking) in the presence of hydrogen and a heterogeneous catalyst. . However, this process has the major drawback of causing a very significant drop in the octane number if the catalyst used is not selective enough. This decrease in the octane number is in particular linked to the hydrogenation of the olefins present in this type of gasoline concomitantly with the hydrodesulphurization. Unlike other hydrotreating processes, the hydrodesulphurization of gasolines must therefore make it possible to respond to a double antagonistic constraint: to ensure deep hydrodesulphurization of gasolines and to limit the hydrogenation of the unsaturated compounds present.

One way to respond to this dual problem consists in using hydrodesulphurization catalysts that are both active in hydrodesulphurization but also very selective in hydrodesulphurization with respect to the hydrogenation reaction of olefins. Thus, in the state of the art, document US 2009/321320 is known, which discloses hydrodesulphurization catalysts which comprise an active metal phase containing cobalt/molybdenum and a support based on high temperature alumina (i.e. say calcined at a temperature above 800° C.) and containing less than 50% by weight of gamma, eta and chi alumina, and with a specific surface area of between 40 and 200 m ² /g. The catalysts are obtained by dry impregnation of an aqueous solution containing cobalt, molybdenum and at least one additive in the form of an organic compound.

Document EP 1892039 describes selective hydrodesulphurization catalysts comprising at least one support, at least one element from group VIII, at least one element from group VIB and phosphorus in which the support can consist essentially of at least one transition alumina , that is to say that it comprises at least 51% by weight of transition alumina, said support possibly having a specific surface of less than 135 m ² /g.

On the other hand, it is known from the prior art that the porous distribution of the catalyst supports can have a beneficial impact on the catalytic performances, in particular the fact of having multimodal porosities.

Document CN109894122 discloses a process for the hydrodesulphurization of a catalytic cracking gasoline (FCC) in the presence of a catalyst comprising an active phase based on cobalt and molybdenum, alkaline dopants, and a mesoporous and macroporous alumina support. , with a specific surface area between 260 and 290 m ² /g, a total pore volume between 0.8 and 2.2 ml/g, pores with a diameter between 10 and 200 nm, in which the volume of the pores with a diameter between 10 and 50 nm represents between 10 and 50% of the total porous volume of the support, and the volume of the pores with a diameter between 50 and 200 nm represents between 50 and 90% of the total porous volume of the support. The support used comprises a monomodal distribution of mesopores and a monomodal distribution of macropores.

Document CN109420504 discloses a process for the hydrodesulfurization of a catalytic cracking gasoline (FCC) in the presence of a catalyst comprising an active phase based on cobalt and molybdenum, and a mesoporous and macroporous alumina support, in which the volume of pores with a diameter of between 60 and 200 nm represents between 1 and 80% of the total pore volume of the support, and the volume of pores with a diameter of between 5 and 50 nm represents between 20 and 70% of the total pore volume of the support. The support used comprises a monomodal distribution of mesopores and a monomodal distribution of macropores. Document US6,589,908 discloses a process for the preparation of a catalyst support, which does not contain macroporosity and has a bimodal porous structure in the mesoporosity such that the two modes of porosity are separated by 1 to 20 nm.

There is therefore still today a keen interest among refiners for hydrodesulphurization catalysts, in particular gasoline cuts, which have improved catalytic performance, in particular in terms of catalytic activity in hydrodesulphurization and/or selectivity and which thus, once placed implemented make it possible to produce gasoline with a low sulfur content without a severe reduction in the octane number.

In this context, one of the objectives of the present invention is to propose a process for the hydrodesulphurization of an olefinic gasoline cut containing sulfur, in the presence of a supported catalyst having performances in activity and in selectivity, at least as good, or even better than the methods known from the state of the art.

Objects of the invention

The subject of the present invention is a process for the hydrodesulphurization of an olefinic gasoline cut containing sulfur in which said gasoline cut is brought into contact with hydrogen and a catalyst, said hydrodesulphurization process being carried out at a temperature between 200 and 400°C, a total pressure of between 1 and 3 MPa, an hourly volume velocity, defined as being the volume flow rate of charge relative to the volume of the catalyst, of between 1 and 10 h ^-1 , and a volume ratio hydrogen/ gasoline cut between 100 and 600 Nl/l, said catalyst comprising at least one metal from group VIB, at least one metal from group VIII, and a macroporous and mesoporous alumina support comprising a bimodal distribution of mesopores, and in which:

- the volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm corresponds between 10 and 30% by volume of the total pore volume of said support;

- the volume of mesopores with a diameter greater than or equal to 18 nm and less than 50 nm corresponds between 30 and 50% by volume of the total pore volume of said support;

- the volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds between 30 to 50% by volume of the total pore volume of said support.

The applicant has surprisingly discovered that the use of a catalyst based on at least one metal from group VIB, at least one metal from group VIII, on a mesoporous and macroporous support, having both a mesoporous bimodal, with a high mesoporous volume coupled to a determined macroporous volume makes it possible to improve the catalytic performance of said process, in terms of catalytic activity and in terms of selectivity. This results in better feed conversion under identical operating conditions than those used in the prior art. Indeed, without being linked to any scientific theory, the use of such a catalyst in a gasoline hydrodesulphurization process improves the phenomena of internal diffusion of the reactants and of the products by the presence of populations of different sizes of mesopores. In addition, the combined presence of macroporosity is particularly judicious when the feed to be treated contains a significant quantity of reactive olefins (unsaturated compounds), in particular diolefins, which is the case of gasolines, which can give rise to the formation of gums and thus blocking the porosity of the catalyst without the presence of macroporosity. The optimization of the porosity ranges of the catalysts therefore constitutes a decisive element on the performance in a gasoline hydrodesulphurization process.

According to one or more embodiments, said support comprises a specific surface of between 50 and 210 m ² /g.

According to one or more embodiments, said support comprises a total pore volume of between 0.7 and 1.3 mL/g.

According to one or more embodiments, the volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm corresponds between 15 and 25% by volume of the total pore volume of said support.

According to one or more embodiments, the volume of mesopores with a diameter greater than or equal to 18 nm and less than 50 nm corresponds between 35 and 45% by volume of the total pore volume of said support.

According to one or more embodiments, the volume of the macropores with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds between 35 to 50% by volume of the total porous volume of said support.

According to one or more embodiments, the metal content of group VIB of said catalyst, expressed in oxide form, is between 1 and 30% by weight relative to the total weight of the catalyst.

According to one or more embodiments, the group VIII metal content of said catalyst, expressed in oxide form, is between 0.5 and 10% by weight relative to the total weight of said catalyst.

In one or more embodiments, the Group VIII metal is cobalt. In one or more embodiments, the Group VIB metal is molybdenum.

According to one or more embodiments, said catalyst further comprises phosphorus, the phosphorus content, expressed in P2O5 form, is between 0.1 and 10% by weight relative to the total weight of said catalyst.

According to one or more embodiments, the porous distribution of the mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is centered on a range of values comprised between 10.5 and 14.5 nm.

According to one or more embodiments, the porous distribution of the mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is centered on a range of values comprised between 22 and 28 nm.

According to one or more embodiments, the gasoline is a catalytic cracked gasoline.

According to one or more embodiments, the support is in the form of balls with a diameter of between 2 and 4 mm.

According to one or more embodiments, said support in the form of beads is obtained according to the following steps: s1) dehydration of an aluminum hydroxide or an aluminum oxyhydroxide at a temperature between 400°C and 1200°C , preferably between 600° C. and 900° C., for a time of between 0.1 second and 5 seconds, preferably between 0.1 second and 4 seconds, to obtain an alumina powder; s2) shaping said alumina powder obtained in step s1) in the form of balls; s3) heat treatment of the alumina balls obtained in step s2) at a temperature greater than or equal to 200° C.; s4) hydrothermal treatment of the alumina balls obtained at the end of step s3) by impregnation with water or an aqueous solution, then residence in an autoclave at a temperature between 100° C. and 300° C.; s5) calcining the alumina balls obtained at the end of step s4) at a temperature between 500°C and 820°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 BET specific surface is measured by physisorption with nitrogen according to standard ASTM D3663-03, method described in the work Rouquerol F.; Rouquerol J.; Singh K. “Adsorption by Powders & Porous Solids: Principle, methodology and applications”, Academie Press, 1999.

In the present description, according to the IUPAC convention, micropores are understood to mean pores whose diameter is less than 2 nm, that is to say 0.002 μm; by mesopores pores whose diameter is greater than 2 nm, ie 0.002 pm and less than 50 nm, ie 0.05 pm and by macropores pores whose diameter is greater than or equal to 50 nm , i.e. 0.05 µm.

In the following description of the invention, the term “total pore volume of the alumina or of the catalyst” means 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 book “Engineering techniques, analysis and characterization treatise”, p.1050-5, written by Jean Charpin and Bernard Rasneur.

In order to obtain better accuracy, the value of the total pore volume in ml/g given in the following text corresponds to the value of the total mercury volume (total pore volume measured by intrusion with a mercury porosimeter) in ml/g measured on the sample minus the mercury volume value in ml/g measured on the same sample for a pressure corresponding to 30 psi (approximately 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 macropore volume of the catalyst 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 with an apparent diameter greater than 50 nm.

The mesoporous volume of the catalyst 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 with an apparent diameter of between 2 and 50 nm.

When the incremental pore volume measured by mercury porosimetry is plotted against the pore diameter, the pore modes correspond to the inflection points of the function represented.

The contents of metallic elements (group VIII metal, group VIB metal) and phosphorus are measured by X-ray fluorescence.

2. Description

Catalyst

The catalyst used in the context of the hydrodesulfurization process according to the invention comprises an active phase comprising, preferably consisting of, at least one metal from group VIB, at least one metal from group VIII and optionally phosphorus.

The group VIB metal present in the active phase of the catalyst is preferably chosen from molybdenum and tungsten, more preferably molybdenum. The group VIII metal present in the active phase of the catalyst is preferably chosen from cobalt, nickel and the mixture of these two elements, more preferably cobalt.

The total content of group VIII metal is generally between 0.5 and 10% by weight, expressed in the oxide form of the group VIII metal relative to the total weight of the catalyst, preferably between 1 and 10% by weight, preferably between 1 and 7% by weight, very preferably between 1 and 6% by weight and even more preferably between 1.5 and 5% by weight relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO or NiO respectively.

The group VIB metal content is generally between 1 and 30% by weight, expressed in the oxide form of the group VIB metal relative to the total weight of the catalyst, preferably between 3 and 20% by weight, preferably between 5 and 18 % by weight, very preferably between 7 and 14% by weight relative to the total weight of the catalyst. When the metal is molybdenum or tungsten, the metal content is expressed in MO0 ₃ OR W0 ₃ respectively. The phosphorus content, when it is present in the catalyst, is between 0.1 and 10% by weight of P2O5 relative to the total weight of catalyst, preferably between 0.5 and 5% by weight of P2O5 relative to the weight total catalyst, and even more preferably between 1 and 3% by weight of P2O5 relative to the total weight of catalyst.

The catalyst generally comprises a specific surface of between 50 and 200 m ² /g, preferably between 60 and 170 m ² /g and preferably between 70 and 130 m ² /g.

The pore volume of the catalyst is generally between 0.5 mL/g and 1.3 mL/g, preferably between 0.6 mL/g and 1.1 mL/g.

Alumina support

The alumina support of the catalyst used in the context of the hydrodesulfurization process according to the invention is a macroporous and mesoporous alumina support comprising a bimodal distribution of mesopores in which:

Preferably, the volume of the mesopores of the support with a diameter greater than or equal to 2 nm and less than 18 nm corresponds to between 15 and 25% by volume of the total porous volume of said support.

Preferably, the volume of the mesopores of the support with a diameter greater than or equal to 18 nm and less than 50 nm corresponds to between 35 and 45% by volume of the total porous volume of said support.

Preferably, the volume of the macropores of the support with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds between 35 to 50% by volume of the total porous volume of said support.

In one embodiment according to the invention, the porous distribution of the mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is centered on a range of values comprised between 10.5 and 14.5 nm, preferably between 12 and 13 nm. In one embodiment according to the invention, the porous distribution of the mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is centered on a range of values comprised between 22 and 28 nm, preferably between 23 and 27 nm.

The support generally comprises a specific surface of between 50 and 210 m ² /g, preferably between 70 and 180 m ² /g, and even more preferably between 70 and 160 m ² /g.

The pore volume of the support is generally between 0.7 mL/g and 1.3 mL/g, preferably between 0.8 mL/g and 1.2 mL/g.

Advantageously, the support is in the form of balls with a diameter of between 0.8 and 10 mm, preferentially between 1 and 5 mm, and more preferentially between 2 and 4 mm.

The alumina support of the catalyst used in the context of the hydrodesulphurization process according to the invention can be synthesized by any method known to those skilled in the art.

According to a preferred embodiment, the alumina support used according to the invention is in the form of beads. According to this preferred mode, the preparation of the support comprises the following steps: s1) dehydration of an aluminum hydroxide or an aluminum oxyhydroxide at a temperature between 400° C. and 1200° C., preferably between 600° C. and 900° C., for a period of between 0.1 second and 5 seconds, preferably between 0.1 second and 4 seconds, to obtain an alumina powder; s2) shaping of said alumina powder obtained in step s1) in the form of balls; s3) heat treatment of the beads obtained in step s2) at a temperature greater than or equal to 200° C.; s4) hydrothermal treatment of said alumina balls obtained at the end of step s3) by impregnation with water or a preferentially acidic aqueous solution, then residence in an autoclave at a temperature between 100° C. and 300° C. C, preferably between 150°C and 250°C; s5) calcining the alumina balls obtained at the end of step s4) at a temperature between 500°C and 820°C.

Steps s1) to s5) are described in detail below. According to step s1), dehydration of an aluminum hydroxide or an aluminum oxyhydroxide is carried out at a temperature between 400° C. and 1200° C., preferably between 600° C. and 900° C., for a period of between 0.1 second and 5 seconds, preferably between 0.1 second and 4 seconds, to obtain an alumina powder. The aluminum hydroxide can be chosen from hydrargillite, gibbsite or bayerite. The aluminum oxyhydroxide can be chosen from boehmite or diaspore.

Preferably, step s1) is carried out using hydrargillite.

Generally, step s1) is carried out in the presence of a current of hot gas, such as dry air or humid air, allowing the evaporated water to be eliminated and carried away quickly.

Generally, the active alumina powder obtained after the dehydration of the aluminum hydroxide or oxyhydroxide is ground to a particle size of between 10 to 200 μm.

Generally, the active alumina powder obtained after the dehydration of aluminum hydroxide or oxyhydroxide is washed with water or an acidic aqueous solution. When the washing step is carried out with an aqueous acid solution, any mineral or organic acid may be used, preferably nitric acid, hydrochloric acid, perchloric or sulfuric acid for mineral acids, and a carboxylic acid (formic, acetic or malonic acid), a sulphonic acid (para-toluene sulphonic acid) or a sulfuric ester (lauryl sulphate) for organic acids.

According to step s2), the said alumina powder obtained at the end of step s1) is shaped.

The shaping of said alumina powder is carried out so as to obtain balls, called granulation, is generally carried out by means of rotating technology such as a rotating bezel or a rotating drum. This type of process makes it possible to obtain balls of controlled diameter and pore distributions, these dimensions and these distributions being, in general, created during the agglomeration step.

The porosity can be created by various means, such as the choice of the particle size of the alumina powder or the agglomeration of several alumina powders of different particle sizes. Another method consists in mixing with the alumina powder, before or during the agglomeration step, one or more compounds, called porogens, which disappear on heating and thus create porosity in the balls. As pore-forming compounds used, mention may be made, by way of example, of wood flour, charcoal, activated carbon, black carbon, sulfur, tars, plastics or emulsions of plastics such as polyvinyl chloride, polyvinyl alcohols, naphthalene or the like. The quantity of pore-forming compounds added is determined by the volume desired to obtain beads with a raw filling density of between 500 and 1100 kg/m ³ , preferably between 700 and 950 kg/m ³ , and with a diameter of between 0.8 and 10 mm, preferably between 1 and 5 mm, and ink more preferably between 2 and 4 mm. A selection by sieving of the balls obtained can be carried out according to the desired particle size.

According to step s3), a heat treatment is carried out on the alumina powder shaped in the form of beads obtained at the end of step s2) at a temperature greater than or equal to 200° C., preferably between between 200° C. and 1200° C., preferably between 300 and 900° C., very preferably between 400° C. and 750° C., for a duration generally comprised between 1 and 24 hours, preferably between 1 and 6 hours. The beads obtained at this intermediate step comprise a specific surface between 50 and 420 m ² /g, preferably between 60 and 350 m ² /g, and even more preferably between 80 and 300 m ² /g.

According to step s4), the alumina balls obtained at the end of step s3) undergo a hydrothermal treatment by impregnation with water or a preferably acidic aqueous solution, then stay in an autoclave at a temperature between between 100°C and 300°C, preferably between 150°C and 250°C.

The hydrothermal treatment is generally carried out at a temperature of 100° C. to 300° C., preferentially from 150° C. to 250° C., for a duration greater than 45 minutes, preferentially from 1 to 24 hours, very preferentially from 1.5 to 12 hours. The hydrothermal treatment is generally carried out using an aqueous acid solution comprising one or more mineral and/or organic acids, preferably nitric acid, hydrochloric acid, perchloric acid, sulfuric acid, weak whose solution has a pH lower than 4 such as acetic acid or formic acid. Generally, said acidic aqueous solution also comprises one or more compounds capable of releasing anions capable of combining with aluminum ions, preferably compounds comprising a nitrate ion (such as aluminum nitrate), chloride, sulphate, perchlorate, chloroacetate, trichloroacetate, bromoacetate, dibromoacetate, and anions of general formula: R-COO such as formates and acetates. According to step s5), the alumina balls obtained at the end of step s4) undergo calcination at a temperature of between 500° C. and 820° C., preferably between 550° C. and 750° C., and for a period generally between 1 and 24 hours, preferably between 1 and 6 hours. At the end of this step, the alumina balls obtained comprise a specific surface between 50 and 210 m ² /g, preferably between 70 and 180 m ² /g, and even more preferably between 70 and 160 m ² /g .

The catalyst used in the context of the hydrodesulphurization process according to the invention can be prepared by means of any technique known to those skilled in the art, and in particular by impregnation of the elements of groups VIII and VIB, optionally phosphorus, on the support. selected.

According to a first mode of implementation, said components of metals of group VIB, of group VIII and of phosphorus are deposited on said support, by one or more steps of co-impregnations, that is to say that said components of the metals of group VIB, of group VIII and of phosphorus are introduced simultaneously into said support. The co-impregnation step(s) is (are) preferably carried out by dry impregnation or by impregnation in excess of solution. When this first mode comprises the implementation of several co-impregnation steps, each co-impregnation step is preferably followed by an intermediate drying step generally at a temperature below 200° C., advantageously between 50 and 180° C. C, preferably between 60 and 150°C, very preferably between 75 and 140°C.

According to a preferred embodiment by co-impregnation, the impregnation solution is preferably an aqueous solution. Preferably, the aqueous impregnation solution when it contains cobalt, molybdenum and phosphorus is prepared under pH conditions favoring the formation of heteropolyanions in solution. For example, the pH of such an aqueous solution is between 1 and 5.

According to a second mode of implementation, the catalyst precursor is prepared by carrying out the successive depositions and in any order of a component of a group VIB metal, of a component of a group VIII metal and optionally phosphorus on said support. The deposits can be made by dry impregnation, by excess impregnation or else by precipitation-deposition according to methods well known to those skilled in the art. In this second embodiment, the deposition of the components of the metals of groups VIB and VIII and optionally phosphorus can be carried out by several impregnations with an intermediate drying step between two successive impregnations generally at a temperature below 200°C, advantageously between 50 and 180°C, preferably between 60 and 150°C, very preferably between 75 and 140°C.

Whatever the mode of deposition of metals and phosphorus used, the solvent which enters into the composition of the impregnation solutions is chosen so as to solubilize the metal precursors of the active phase, such as water or a solvent organic (for example an alcohol).

By way of example, among the sources of molybdenum, use may be made of oxides and hydroxides, molybdic acids and their salts, in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H3PM012O40), and their salts, and optionally silicomolybdic acid (HUSiMo^O^) and its salts. The sources of molybdenum can also be any heteropolycompound of Keggin, lacunary Keggin, substituted Keggin, Dawson, Anderson, Strandberg type, for example. Preferably, molybdenum trioxide and the heteropolycompounds of Keggin, lacunary Keggin, substituted Keggin and Strandberg type are used.

The tungsten precursors which can be used are also well known to those skilled in the art. For example, among the sources of tungsten, it is possible to use oxides and hydroxides, tungstic acids and their salts, in particular ammonium salts such as ammonium tungstate, ammonium metatungstate, phosphotungstic acid and their salts, and optionally silicotungstic acid (H ₄ SiWi 04o) and its salts. The tungsten sources can also be any heteropolycompound of Keggin, lacunary Keggin, substituted Keggin, Dawson type, for example. Preferably, ammonium oxides and salts are used, such as ammonium metatungstate or heteropolyanions of Keggin, lacunary Keggin or substituted Keggin type.

The cobalt precursors which can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. Cobalt hydroxide and cobalt carbonate are preferably used.

The nickel precursors which can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. Nickel hydroxide and nickel hydroxycarbonate are preferably used.

The phosphorus can advantageously be introduced into the catalyst at various stages of its preparation and in various ways. The phosphorus can be introduced during the shaping of said alumina support, or preferably after this shaping. He can be advantageously introduced alone or as a mixture with at least one of the metals of group VIB and VIII. The phosphorus is preferably introduced as a mixture with the precursors of the metals of group VIB and of group VIII, in whole or in part on the shaped alumina support, by dry impregnation of said alumina support using of a solution containing the metal precursors and the phosphorus precursor. The preferred source of phosphorus is orthophosphoric acid H ₃ P0 ₄ , but its salts and esters such as ammonium phosphates or mixtures thereof are also suitable. The phosphorus may also be introduced together with the group VIB element(s) in the form of, for example, heteropolyanions of Keggin, lacunary Keggin, substituted Keggin or of the Strandberg type.

At the end of the step or steps of bringing the metals of group VIII, group VIB and phosphorus into contact with the support, the precursor of the catalyst is subjected to a drying step carried out by any technique known to those skilled in the art. . It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out at atmospheric pressure. This step is carried out at a temperature below 200°C, preferably between 50 and 180°C, preferably between 60°C and 150°C and very preferably between 75°C and 140°C.

The drying step is advantageously carried out in a traversed bed using air or any other hot gas. Preferably, when the drying is carried out in a traversed bed, the gas used is either air or an inert gas such as argon or nitrogen. Very preferably, the drying is carried out in a traversed bed in the presence of air.

Preferably, this drying step lasts between 30 minutes and 24 hours, and preferably between 1 hour and 12 hours.

At the end of the step of the drying step, a dried catalyst is obtained which can be used as a hydrotreating catalyst after an activation phase (sulphidation step).

According to a variant, the dried catalyst can be subjected to a subsequent calcination step, for example in air, at a temperature greater than or equal to 200°C. The calcination is generally carried out at a temperature less than or equal to 600°C, and preferably between 200°C and 600°C, and in a particularly preferred manner between 250°C and 500°C. The calcining time is generally between 0.5 hour and 16 hours, preferably between 1 hour and 5 hours. It is generally carried out under air. Calcination transforms the precursors of group VIB and VIII metals into oxides. Before its use as a hydrotreating catalyst, it is advantageous to subject the dried or optionally calcined catalyst to a sulfurization step (activation phase). This activation phase is carried out by methods well known to those skilled in the art, and advantageously under a sulfo-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. The hydrogen sulfide can be used directly or generated by a sulfide agent (such as dimethyl disulfide).

Gasoline hydrodesulfurization process

The hydrotreating process consists of bringing the olefinic gasoline cut containing sulfur into contact with a catalyst as described above and hydrogen under the following conditions:

- a temperature between 200°C and 400°C, preferably between 230°C and 330°C;

- at a total pressure of between 1 and 3 MPa, preferably between 1.5 and 2.5 MPa;

- an hourly volume velocity (VVH), defined as being the volume flow rate of charge relative to the volume of catalyst, between 1 and 10 h ^-1 , preferably between 2 and 6 h ^-1 ;

- a hydrogen/petrol feedstock ratio of between 100 and 600 N l/l, preferably between 200 and 400 N l/l.

Thus, the method according to the invention makes it possible to treat any type of olefinic gasoline cut containing sulfur, such as for example a cut from a coking unit (coking according to the Anglo-Saxon terminology), visbreaking (visbreaking according to the Anglo-Saxon terminology), steam cracking (steam cracking according to the Anglo-Saxon terminology) or catalytic cracking (FCC, Fluid Catalytic Cracking according to the Anglo-Saxon terminology). This gasoline may optionally be composed of a significant fraction of gasoline from other production processes such as atmospheric distillation (gasoline from direct distillation (or straight run gasoline according to Anglo-Saxon terminology) or from conversion (gasoline from coking or steam cracking) Said feed preferably consists of a gasoline cut from a catalytic cracking unit.

The feed is advantageously a gasoline cut containing sulfur compounds and olefins and has a boiling point of between 30 and less than 250°C, preferably between 35°C and 240°C, and preferably between 40°C and 220°C. The sulfur content of gasoline cuts produced by catalytic cracking (FCC) depends on the sulfur content of the FCC-treated feedstock, the presence or not of a pretreatment of the FCC feedstock, as well as the end point of the chopped off. Generally, the sulfur contents of an entire gasoline cut, in particular those originating from the FCC, are greater than 100 ppm by weight and most of the time greater than 500 ppm by weight. For gasolines having end points higher than 200° C., the sulfur contents are often higher than 1000 ppm by weight, they can even in certain cases reach values of the order of 4000 to 5000 ppm by weight.

In addition, gasolines from catalytic cracking units (FCC) contain, on average, between 0.5% and 5% by weight of diolefins, between 20% and 50% by weight of olefins, between 10 ppm and 0.5% weight of sulfur of which generally less than 300 ppm of mercaptans. Mercaptans are generally concentrated in the light fractions of gasoline and more specifically in the fraction whose boiling point is below 120°C.

It should be noted that the sulfur compounds present in gasoline can also comprise heterocyclic sulfur compounds, such as for example thiophenes, alkylthiophenes or benzothiophenes. These heterocyclic compounds, unlike mercaptans, cannot be eliminated by extractive processes. These sulfur compounds are therefore removed by hydrotreating, which leads to their transformation into hydrocarbons and FiS.

Preferably, the gasoline treated by the process according to the invention is a heavy gasoline (or FICN for Fleavy Cracked Naphtha according to the Anglo-Saxon terminology) resulting from a distillation step aimed at separating a large cut from the gasoline resulting a cracking process (or FRCN for Full Range Cracked Naphtha according to the Anglo-Saxon terminology) into a light gasoline (LCN for Light Cracked Naphtha according to the Anglo-Saxon terminology) and a heavy gasoline FICN. The cut point of light gasoline and heavy gasoline is determined in order to limit the sulfur content of light gasoline and to allow its use in the gasoline pool preferably without additional post-treatment. Advantageously, the large FRCN cut is subjected to a selective hydrogenation step before the distillation step.

Examples

Example 1: Catalyst A (according to the invention)

Support S1 of catalyst A is prepared by dehydration of hydrargillite ( ^EMPLURA® , Merck) in order to obtain an alumina powder. The temperature is set at 800° C. and the contact time of the material to be dehydrated with a flow of dry air is 1 second. The powder of alumina obtained is ground to a particle size of between 10 and 200 μm and then washed three times with a volume of distilled water equal to twice the volume of the powder used. Said alumina powder is shaped in the presence of carbon black (N990 Thermax ^® ) with a plate granulator (GRELBEX P30) equipped with a conical cylindrical bowl at an angle of 30° and a rotation speed of 40 revolutions per minute so as to obtain balls with a diameter mostly comprised between 2 and 4 mm after sieving the solid. The quantity of carbon black is adjusted to obtain a raw filling density of the objects of 800 kg/m ³ . Said balls undergo a heat treatment in air at 720° C. so as to give them a specific surface area of 200 m ² /g. Next, a hydrothermal treatment is applied to said balls by impregnation of the porous volume with an aqueous solution of nitric acid (0.1 N, Merck). The hydrothermal treatment is carried out at a temperature of 200° C. for 6.5 hours, in a rotating basket autoclave. The balls thus obtained undergo a final calcination treatment in air at 650° C. for 2 hours. Support S1 has a specific surface of 141 m ² /g, a total pore volume of 0.97 mL/g as well as the following pore distribution given by mercury porosimetry:

- a volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm, whose pore distribution is centered on 13 nm, of 0.15 mL/g corresponding to 15% of the total pore volume;

- a volume of mesopores with a diameter greater than or equal to 18 nm and less than 50 nm, whose pore distribution is centered on 26 nm, of 0.43 mL/g corresponding to 44% of the total pore volume;

- a volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm of 0.39 mL/g, corresponding to 40% of the total pore volume.

Support S1 has a water uptake volume of 0.95 mL/g. The impregnation solution is prepared by heating at 90°C for 3 hours 1.15 grams of molybdenum oxide (MOO3 >99.5%, Merck), 0.28 grams of cobalt hydroxide (CO(OH ) 95%, Merck), and 0.26 grams of phosphoric acid (H3PO4 at 85% by weight in water, Merck) in 9.3 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. The solid is then calcined in air at 450° C. for 2 hours. Catalyst A obtained contains 1.9% by weight of CoO, 10% by weight of MOO3 and 1.4% by weight of P2O5 relative to the total weight of the catalyst. Catalyst A has a total pore volume of 0.88 mL/g and a specific surface of 118 m ² /g. : Catalyst B (according to the invention)

Catalyst B is obtained by dry impregnation of the alumina support S1 with an aqueous solution prepared from 1.35 grams of ammonium heptamolybdate ((NH ₄ ) ₆ Mq ₇ q _24.4H 0 99.98 %, Merck), 1.38 grams of cobalt nitrate (Co(N0 ₃ ) ₂ .6H ₂ 0 98%, Merck) in 9.4 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. The solid is then calcined in air at 450° C. for 2 hours. Catalyst B obtained contains 3.1% by weight of CoO and 9.6% by weight of Mo0 ₃ relative to the total weight of the catalyst. Catalyst B has a total pore volume of 0.89 mL/g and a specific surface of 124 m ² /g.

Example 3: Non-conforming catalyst C (monomodal macroporous and large mesoporous catalyst)

Support S2 of catalyst C is prepared by dehydration of hydrargillite ( ^EMPLURA® , Merck) in order to obtain an active alumina powder. The temperature is set at 800° C. and the contact time of the material to be dehydrated with a flow of dry air is 1 second. The active alumina powder obtained is ground to a particle size of between 10 and 200 μm and is then washed three times with a volume of distilled water equal to twice the volume of the powder used. Said active alumina powder is shaped with a plate granulator (GRELBEX P30) equipped with a conical cylindrical bowl at an angle of 30° and a rotation speed of 40 revolutions per minute so as to obtain balls with a diameter mainly between 2 and 4 mm (after sieving the solid) and a raw filling density of the objects of 780 kg/m ³ . Said balls undergo a heat treatment in air at 700° C. so as to give them a specific surface area of 250 m ² /g. Next, a hydrothermal treatment is applied to said balls by impregnation of the porous volume with an aqueous solution of nitric acid (0.1 N, Merck). The hydrothermal treatment is carried out at a temperature of 200° C. for 6.5 hours, in a rotating basket autoclave. The balls thus obtained undergo a final calcination treatment in air at 950° C. for 2 hours. The support S2 has a specific surface of 71 m ² /g, a total porous volume of 0.56 mL/g as well as the following porous distribution given by mercury porosimetry:

- a volume of mesopores with a diameter greater than or equal to 10 nm and less than 50 nm, whose pore distribution is centered on 20 nm, of 0.35 mL/g corresponding to 63% of the total pore volume;

- a volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm of 0.21 mL/g, corresponding to 38% of the total pore volume. Support S2 has a water uptake volume of 0.54 mL/g. The impregnation solution is prepared by heating at 90°C for 3 hours 1.15 grams of molybdenum oxide (MOO3 >99.5%, Merck), 0.28 grams of cobalt hydroxide (CO(OH ) 95%, Merck), and 0.26 grams of phosphoric acid (H3PO4 at 85% by weight in water, Merck) in 5.2 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. The solid is then calcined in air at 450° C. for 2 hours. Catalyst C obtained contains 1.9% by weight of CoO, 10% by weight of MOO3 and 1.4% by weight of P ₂ 0 relative to the total weight of the catalyst. Catalyst C has a total pore volume of 0.47 mL/g and a specific surface of 62 m ² /g.

A commercial support S3 (SA52124, ^UniSpheres® NorPro) is provided in the form of beads with a diameter of between 2 and 4 mm. The S3 support has a specific surface area of 8 m ² /g, a total pore volume of 0.33 mL/g as well as the following pore distribution given by mercury porosimetry:

- a volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm of 0.33 mL/g, corresponding to 100% of the total pore volume.

Support S3 has a water uptake volume of 0.37 mL/g. The impregnation solution is prepared by heating at 90°C for 3 hours 1.15 grams of molybdenum oxide (MOO3 >99.5%, Merck), 0.28 grams of cobalt hydroxide (CO(OH ) ₂ 95%, Merck), and 0.26 grams of phosphoric acid (H ₃ P0 ₄ at 85% by weight in water, Merck) in 3.5 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. At the end of the two impregnation steps, the solid is then calcined in air at 450° C. for 2 hours. Catalyst D obtained contains 1.9% by weight of CoO, 10% by weight of MOO3 and 1.4% by weight of P ₂ Os relative to the total weight of the catalyst. Catalyst D has a total pore volume of 0.21 mL/g and a specific surface of 5 m ² /g.

A commercial support S4 (SA6578, NorPro) is supplied in the form of an extrudate of 5 mm in diameter. The S4 support has a specific surface of 175 m ² /g, a total pore volume of 0.82 mL/g as well as the following pore distribution given by mercury porosimetry: - a volume of mesopores with a diameter greater than or equal to 2 nm and less than or equal to 20 nm, whose pore distribution is centered on 13 nm, of 0.82 mL/g corresponding to 100% of the total pore volume.

The S4 support has a water uptake volume of 0.81 mL/g. The impregnation solution is prepared by heating at 90° C. for 3 hours 1.15 grams of molybdenum oxide (Mo0 ₃ >99.5%, Merck), 0.28 grams of cobalt hydroxide (CO( OH) ₂ 95%, Merck), and 0.26 grams of phosphoric acid (H ₃ P0 ₄ 85% by weight in water, Merck) in 7.9 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. The solid is then calcined in air at 450° C. for 2 hours. The catalyst E obtained contains 1.9% by weight of CoO, 10% by weight of Mo0 ₃ and 1.4% by weight of P2O5 relative to the total weight of the catalyst. Catalyst E has a total pore volume of 0.74 mL/g and a specific surface of 136 m ² /g.

Example 6: Non-compliant catalyst F (monomodal macroporous and small mesoporous catalyst)

A commercial support S5 (SA6176, NorPro) is supplied in the form of an extrudate 1.6 mm in diameter. The S5 support has a specific surface of 250 m ² /g, a total pore volume of 1.05 mL/g as well as the following porous distribution given by mercury porosimetry:

- a volume of mesopores with a diameter greater than or equal to 2 nm and less than or equal to 20 nm, whose pore distribution is centered on 7 nm, of 0.68 mL/g corresponding to 65% of the total pore volume;

- a volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm of 0.37 mL/g, corresponding to 35% of the total pore volume.

The S5 support has a water uptake volume of 1.02 mL/g. The impregnation solution is prepared by heating at 90° C. for 3 hours 1.15 grams of molybdenum oxide (Mo0 ₃ >99.5%, Merck), 0.28 grams of cobalt hydroxide (CO( OH) ₂ 95%, Merck), and 0.26 grams of phosphoric acid (H ₃ P0 ₄ at 85% by weight in water, Merck) in 10.0 mL of distilled water. After dry impregnation of 10 grams of support and a maturation step for 12 hours in an atmosphere saturated with humidity, the solid is dried for 12 hours at 120°C. The solid is then calcined in air at 450° C. for 2 hours. The catalyst F obtained contains 1.9% by weight of CoO, 10% by weight of Mo0 ₃ and 1.4% by weight of P ₂ Os relative to the total weight of the catalyst. Catalyst F has a total pore volume of 0.87 mL/g and a specific surface of 211 m ² /g. implemented in a hydrodesulfurization reactor

In this example, the performances of catalysts A to F are evaluated in the hydrodesulphurization of a catalytic cracking gasoline.

A representative model charge of a catalytic cracked gasoline (FCC) containing 10% by weight of 2,3-dimethylbut-2-ene and 0.33% by weight of 3-methylthiophene (i.e. 1000 ppm by weight of sulfur in the charge) is used for the evaluation of the catalytic performances of the various catalysts. The solvent used is heptane.

The hydrodesulfurization reaction (FIDS) is carried out in a fixed-bed reactor passed through under a total pressure of 1.5 MPa, at 210° C., at VVFI = 6 h ^-1 (VVFI = volume flow rate of charge/volume of catalyst ), and a Fl/charge volume ratio of 300 N l/l, in the presence of 4 mL of catalyst. Prior to the FIDS reaction, the catalyst is sulfurized in-situ at 350° C. for 2 hours under a flow of hydrogen containing 15% mol of FhS at atmospheric pressure.

Each of the catalysts is successively placed in said reactor. Samples are taken at different time intervals and are analyzed by gas phase chromatography in order to observe the disappearance of the reagents and the formation of the products.

The catalytic performances of the catalysts are evaluated in terms of catalytic activity and selectivity. The hydrodesulfurization activity (FIDS) is expressed from the rate constant for the FIDS reaction of 3-methylthiophene (kFIDS), normalized by the volume of catalyst introduced and assuming first-order kinetics with respect to the sulfur compound. The olefin hydrogenation activity (FlydO) is expressed from the rate constant of the hydrogenation reaction of 2,3-dimethylbut-2-ene, normalized by the volume of catalyst introduced and assuming a kinetics of order 1 with respect to the olefin.

Catalyst selectivity is expressed by the normalized rate constant ratio kFIDS/kFIydO. The kFIDS/kFIydO ratio will be higher the more selective the catalyst. The values obtained are normalized by taking catalyst A as reference (relative FIDS activity and relative selectivity equal to 100). The performances are therefore the relative FIDS activity and the relative selectivity. Table 1

It therefore emerges that the catalysts according to the invention exhibit better performance in terms of activity and selectivity and therefore underlines the importance of the porosity ranges of the catalyst supports on the performance in a gasoline hydrodesulphurization process. This improvement The selectivity of the catalysts is particularly interesting in the case of an implementation in a process for the hydrodesulfurization of gasoline containing olefins for which it is sought to limit as much as possible the loss of octane due to the hydrogenation of the olefins.

Claims

1. Process for the hydrodesulphurization of an olefinic gasoline cut containing sulfur in which said gasoline cut is brought into contact with hydrogen and a catalyst, said hydrodesulphurization process being carried out at a temperature between 200 and 400° C. , a total pressure of between 1 and 3 MPa, an hourly volumetric speed, defined as being the volume flow rate of charge relative to the volume of the catalyst, of between 1 and 10 h ¹ , and a hydrogen/gasoline cut volume ratio of between 100 and 600 N l/l, said catalyst comprising at least one metal from group VIB, at least one metal from group VIII, and a mesoporous and macroporous alumina support comprising a bimodal distribution of mesopores and in which:

2. Method according to claim 1, in which said support comprises a specific surface of between 50 and 210 m ² /g.

3. Method according to one of claims 1 or 2, wherein said support comprises a total pore volume of between 0.7 and 1.3 mL/g.

4. Method according to any one of claims 1 to 3, in which the volume of mesopores with a diameter greater than or equal to 2 nm and less than 18 nm corresponds to between 15 and 25% by volume of the total pore volume of said support.

5. Method according to any one of claims 1 to 4, in which the volume of mesopores with a diameter greater than or equal to 18 nm and less than 50 nm corresponds to between 35 and 45% by volume of the total pore volume of said support.

6. Method according to any one of claims 1 to 5, in which the volume of macropores with a diameter greater than or equal to 50 nm and less than 8000 nm corresponds to between 35 to 50% by volume of the total pore volume of said support.

7. Process according to any one of claims 1 to 6, in which the metal content of group VIB of said catalyst, expressed in oxide form, is between 1 and 30% by weight relative to the total weight of the catalyst.

8. Process according to any one of claims 1 to 7, in which the metal content of group VIII of said catalyst, expressed in oxide form, is between 0.5 and 10% by weight relative to the total weight of said catalyst.

9. A method according to any one of claims 1 to 8, wherein the Group VIII metal is cobalt.

10. Process according to any one of claims 1 to 9, in which the metal of group VIB is molybdenum.

11. Process according to any one of claims 1 to 10, in which said catalyst further comprises phosphorus, the phosphorus content, expressed as P2O5, is between 0.1 and 10% by weight relative to the total weight of said catalyst.

12. Method according to any one of claims 1 to 11, in which the porous distribution of the mesopores with a diameter greater than or equal to 2 nm and less than 18 nm is centered on a range of values between 10.5 and 14.5 n.

13. Method according to any one of claims 1 to 12, in which the porous distribution of the mesopores with a diameter greater than or equal to 18 nm and less than 50 nm is centered on a range of values comprised between 22 and 28 nm.

14. Process according to any one of claims 1 to 13, in which the gasoline is a catalytic cracked gasoline.

15. Method according to any one of claims 1 to 14, in which the support is in the form of balls with a diameter of between 2 and 4 mm.

16. Process according to claim 15, in which said support is obtained according to the following steps: s1) dehydration of an aluminum hydroxide or an aluminum oxyhydroxide at a temperature between 400°C and 1200°C, preferably between 600° C. and 900° C., for a period of between 0.1 second and 5 seconds, preferably between 0.1 second and 4 seconds, to obtain an alumina powder; s2) shaping of said alumina powder obtained in step s1) in the form of balls; s3) heat treatment of the alumina balls obtained in step s2) at a temperature greater than or equal to 200° C.; s4) hydrothermal treatment of the alumina balls obtained at the end of step s3) by impregnation with water or an aqueous solution, then residence in an autoclave at a temperature between 100° C. and 300° C.; s5) calcining the alumina balls obtained at the end of step s4) at a temperature between 500°C and 820°C.