Method for selective hydrogenation of gasoline in the presence of a catalyst on a mesoporous or macroporous support.

Abstract

A process for the selective hydrogenation of gasoline containing polyunsaturated compounds and light sulfur compounds is disclosed, in which the gasoline, together with hydrogen, is contacted with a catalyst comprising a Group VIB metal, a Group VIII metal, and a mesoporous and macroporous alumina support having a bimodal mesopore distribution: the volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 10 and 30 volume % of the total pore volume of the support; the volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 30 and 50 volume % of the total pore volume of the support; and the volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 30 and 50 volume % of the total pore volume of the support.

Description

[Technical Field]

[0001] The present invention relates to the field of hydrogenation treatment of gasoline fractions, particularly gasoline fractions obtained from fluidized bed catalytic cracking units. More specifically, the present invention relates to the use of catalysts in processes for the selective hydrogenation of gasoline and for increasing the molecular weight of light mercaptans, as well as to processes for the selective hydrogenation of polyunsaturated compounds contained in gasoline to monounsaturated compounds, and for simultaneously increasing the molecular weight of light sulfur compounds by reaction with unsaturated compounds. [Background technology]

[0002] To produce gasoline that meets the new environmental standards, its sulfur content must generally not exceed 50 ppm, and preferably be significantly reduced to below 10 ppm.

[0003] Furthermore, it is well known that converted gasoline, more specifically, that which can amount to 30% to 50% of a gasoline pool, comes from catalytic cracking and has a high content of olefins and sulfur.

[0004] For this reason, nearly 90% of the sulfur present in gasoline can be attributed to gasoline resulting from the catalytic cracking process. These will subsequently be called FCC (fluid catalytic cracking) gasoline. Thus, FCC gasoline is a preferred raw material for the process of the present invention. More generally, the process according to the present invention is applicable to any gasoline fraction that contains a certain proportion of diolefins and may also contain several lighter compounds belonging to the C3 and C4 fractions.

[0005] Gasoline from cracking units is generally rich in olefins and sulfur, but also in diolefins, the content of which can range up to 5% by weight in gasoline from catalytic cracking. Diolefins are unstable compounds that readily polymerize and generally must be removed before any treatment of these gasolines, such as hydrodesulfurization intended to meet specifications regarding the sulfur content in the gasoline. However, this hydrogenation must be selective to diolefins and the hydrogenation of olefins must be limited to limit hydrogen consumption and octane loss from the gasoline. Furthermore, as described in Patent Document 1, it is advantageous to convert the mercaptans by molecular weight increase before the desulfurization step. This is because it allows for the production of a desulfurized gasoline fraction mainly composed of olefins having five carbon atoms by simple distillation without octane loss. The amount of sulfur present in the feedstock is not altered after selective hydrogenation and molecular weight increase of the light sulfur compound, but only the properties of the sulfur are altered by the molecular weight increase of the light sulfur compound.

[0006] In addition, diene compounds present in the raw materials to be processed are unstable and tend to form gums through polymerization. This gum formation leads to the gradual deactivation of the catalyst downstream or the gradual clogging of the hydrodesulfurization reactor. Therefore, in industrial applications, it is important to use catalysts that suppress polymer formation, i.e., catalysts with low acidity or catalysts whose porosity is optimized to promote the continuous extraction of polymer or gum precursors by hydrocarbons in the raw materials, in order to ensure the maximum cycle time of the catalyst.

[0007] From prior art, it is well known that the pore distribution of a catalyst support has a beneficial effect on catalyst performance.

[0008] Patent Document 2 discloses a process for preparing a catalyst support, which does not contain macroporosity and has a mesoporous, bimodal pore structure in which two modes of porosity are spaced 1 to 20 nm apart. This support can be used in a variety of catalytic applications, particularly in hydrogenation, especially in hydrogenated denitrification.

[0009] Patent Document 3 discloses a method for preparing a porous alumina support for use as a hydrogenodesulfurization or hydrogenodemetallation catalyst support, wherein the support is 0.65 to 1.30 cm². 3 The porous carrier comprises two groups of macropores, of which approximately 2 to 20 volume percent relative to the total pore capacity are macropores with diameters between 10,000 angstroms and 100,000 angstroms (1,000 and 10,000 nm), approximately 5 to 30 volume percent relative to the total pore capacity are macropores with diameters between 1,000 angstroms and 10,000 angstroms (100 and 1,000 nm), and approximately 50 to 93 volume percent relative to the total pore capacity are mesopores with pore diameters between 30 angstroms and 1,000 angstroms (3 to 100 nm).

[0010] Patent documents 4, 5, and 6 disclose catalysts for various catalytic applications (propane dehydrogenation, esterification), and these supports have a trimodal pore distribution, with clusters of mesopores concentrated in three peaks between 2 and 4 nm, 5 and 15 nm, and 10 and 40 nm, respectively.

[0011] Patent Document 7 discloses alumina for halide capture, which includes a trimodal porosity, of which 40% to 49% by volume relative to the total pore volume of the carrier are pores having diameters between 15 and 50 nm.

[0012] Finally, Patent Documents 8 and 9 disclose a process for the selective hydrogenation of polyunsaturated compounds using a macroporous catalyst whose capacity is between 10% and 40% of the total pore capacity.

[0013] However, none of the prior art documents describe the use of a process for the selective hydrogenation of gasoline containing polyunsaturated compounds and light sulfur compounds in the presence of a catalyst comprising a support having bimodal mesoporosity with a high mesopore volume coupled with a specific macropore volume.

[0014] In this context, one object of the present invention is to provide a process for simultaneously carrying out the selective hydrogenation of polyunsaturated compounds, more specifically diolefins, and the increase in molecular weight of light sulfur compounds, more specifically mercaptans, in the presence of a supported catalyst having performance at least as good as, or even better than, that of processes known from the prior art in terms of activity and selectivity.

[0015] The applicant has found that the use of a catalyst based on at least one Group VIB metal and at least one Group VIII metal on a mesoporous and macroporous support, having bimodal mesoporosity with a high mesopore volume coupled with a given macropore volume, has better activity and selectivity compared to catalysts disclosed in the prior art, which allows for better conversion of light sulfur compounds while being at least as good as, or even better than, that of diolefin hydrogenation.

[0016] Specifically, without being bound by any scientific theory, the use of such a catalyst in a process for the selective hydrogenation of gasoline improves the phenomenon of internal diffusion of reactants and products due to the presence of a population of mesopores of different sizes. In addition, the associated presence of macroporosity is particularly appropriate when the feedstock to be treated contains significant amounts of reactive olefins (unsaturated compounds), especially diolefins. This applies to gasoline, which can cause the formation of gum content and thus clog the porosity of the catalyst without the presence of macroporosity.

Prior Art Documents

Patent Documents

[0017] [Patent Document 1] European Patent Application Publication No. 01077247 [Patent Document 2] U.S. Patent No. 6,589,908 [Patent Document 3] U.S. Patent No. 5,266,300 [Patent Document 4] Chinese Patent Application Publication No. 108855197 Specification [Patent Document 5] Chinese Patent Application Publication No. 104248987 Specification [Patent Document 6] Chinese Patent Application Publication No. 104248985 Specification [Patent Document 7] U.S. Patent No. 7,790,130 [Patent Document 8] French Patent Application Publication No. 2,895,414 [Patent Document 9] French Patent Application Publication No. 2,895,415 [Overview of the Initiative]

[0018] One subject of the present invention is a process for the selective hydrogenation of gasoline containing a polyunsaturated compound and a light sulfur compound, in which gasoline and hydrogen are heated with a catalyst at temperatures between 80°C and 220°C for 1 hour. -1 and 10h -1 The catalyst is brought into contact with a liquid space velocity between 0.5 and 5 MPa and a pressure between 0.5 and 5 MPa, having a molar ratio of hydrogen to the diolefin to be hydrogenated greater than 1 and less than 100 mol / mol, the catalyst comprising at least one group VIB metal, at least one group VIII metal, and a mesoporous and macroporous alumina support having a bimodal distribution of mesopores: The volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 10 volume% and 30 volume% of the total pore volume of the carrier; The volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier; The volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier.

[0019] According to one or more embodiments, the carrier is 50 and 210 m 2 Includes specific surface area between / g

[0020] According to one or more embodiments, the carrier has a total pore volume between 0.7 and 1.3 ml / g.

[0021] According to one or more embodiments, the volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 15 volume% and 25 volume% of the total pore volume of the carrier.

[0022] According to one or more embodiments, the volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 35 volume% and 45 volume% of the total pore volume of the carrier.

[0023] According to one or more embodiments, the volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 35% and 50% of the total pore volume of the carrier.

[0024] According to one or more embodiments, the content of the group VIB metal in the catalyst, expressed in oxide form, is between 1% and 30% by weight relative to the total weight of the catalyst.

[0025] According to one or more embodiments, the content of the group VIII metal in the catalyst, expressed in oxide form, is between 1% and 20% by weight relative to the total weight of the catalyst.

[0026] According to one or more embodiments, the molar ratio of group VIII metals to group VIB metals is between 0.3 and 3 mol / mol.

[0027] According to one or more embodiments, the Group VIII metal is nickel.

[0028] According to one or more embodiments, the group VIB metal is molybdenum.

[0029] According to one or more embodiments, the pore distribution of mesopores having a diameter of 2 nm or more and less than 18 nm is centered in the range of values ​​between 10.5 and 14.5 nm.

[0030] According to one or more embodiments, the pore distribution of mesopores having a diameter of 18 nm or more and less than 50 nm is centered in the range of values ​​between 22 and 28 nm.

[0031] According to one or more embodiments, the gasoline is catalytic cracking gasoline.

[0032] According to one or more embodiments, the carrier is in the form of beads having a diameter between 2 and 4 mm.

[0033] According to one or more embodiments, when the carrier is in the form of beads, the carrier is obtained by following these steps: Step s1: Dehydrating aluminum hydroxide or aluminum oxyhydroxide at temperatures between 400°C and 1200°C, preferably between 600°C and 900°C, for a period of 0.1 seconds and 5 seconds, preferably between 0.1 seconds and 4 seconds, to obtain alumina powder. Step s2) The alumina powder obtained in step s1) is formed into the form of beads. Step s3) Heat-treats the alumina beads obtained in step s2) at a temperature of 200°C or higher. Step s4) involves hydrothermally treating the alumina beads obtained at the end of step s3) by impregnation with water or an aqueous solution, followed by retention in an autoclave at temperatures between 100°C and 300°C. Step s5) calcinates the alumina beads obtained at the end of step s4) at a temperature between 500°C and 820°C.

[0034] According to one or more embodiments, the catalyst does not contain phosphorus. [Modes for carrying out the invention]

[0035] 1.Definition In the following text, groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, CRC Press, supervised by D.R. Lide, 81st edition, 2000-2001). For example, Group VIII according to the CAS classification corresponds to the metals from columns 8, 9, and 10 according to the new IUPAC classification.

[0036] The BET specific surface area is measured by nitrogen physicoadsorption according to ASTM-D3663-03 standard, based on the method described in "Adsorption by Powders & Porous Solids: Principles, Methodology and Applications" by Rouquerol F., Rouquerol J., and Singh K., Academic Press, 1999.

[0037] In this specification, in accordance with IUPAC rules, “micropore” is understood to mean a pore with a diameter of less than 2 nm, or 0.002 μm; “mesopore” is understood to mean a pore with a diameter greater than 2 nm, or 0.002 μm, and less than 50 nm, or 0.05 μm; and “macropore” is understood to mean a pore with a diameter of 50 nm, or 0.05 μm or more.

[0038] In the following description of the present invention, the “total pore capacity” of alumina or catalyst is understood to mean the capacity measured by mercury porosimetry according to the ASTM-D4284-83 standard, using a surface tension of 484 dynes / cm at a maximum pressure of 4000 bar (400 MPa) and a contact angle of 140°. The wetting angle was assumed to be equal to 140°, following the recommendation of Jean Charpin and Bernard Rasneur in the publication “Techniques de l'ingenieur, traite analysis et caracterisation,” pp. 1050-5.

[0039] For better accuracy, the total pore volume values ​​in ml / g given in the following text correspond to the difference between the total mercury volume in ml / g measured for the same sample (total pore volume measured by mercury intrusion porosimetry) and the same sample's total mercury volume in ml / g measured for the same sample.

[0040] The volumes of macropores and mesopores are measured by mercury intrusion porosimetry according to the ASTM-D4284-83 standard, using a surface tension of 484 dynes / cm and a contact angle of 140° at a maximum pressure of 4000 bar (400 MPa).

[0041] The value at which mercury fills all intergranular voids is set to 0.2 MPa; above this value, mercury is thought to penetrate into the pores of the sample.

[0042] The macropore capacity of a catalyst is defined as the cumulative volume of mercury introduced at pressures between 0.2 MPa and 30 MPa, corresponding to the volume contained in pores with an apparent diameter greater than 50 nm.

[0043] The mesopore capacity of a catalyst is defined as the cumulative volume of mercury introduced at pressures between 30 MPa and 400 MPa, corresponding to the volume contained in pores with apparent diameters between 2 and 50 nm.

[0044] When incremental pore volume, measured by mercury porosimetry, is plotted as a function of pore diameter, the modes of porosity correspond to the inflection points of the plotted function.

[0045] The content of Group VIII and Group VIB metals is measured by X-ray fluorescence. 2. Explanation catalyst The catalyst used in the context of a selective hydrogenation process according to the present invention comprises an active phase formed from at least one group VIB metal and at least one group VIII metal.

[0046] The Group VIB metal present in the active phase of the catalyst is preferably selected from molybdenum and tungsten, and more preferably from molybdenum. The Group VIII metal present in the active phase of the catalyst is preferably selected from cobalt, nickel, and mixtures of these two elements, and more preferably from nickel.

[0047] Preferably, the active phase consists of molybdenum and nickel.

[0048] The total content of Group VIII metals is generally between 1% and 20% by weight, preferably between 2% and 15% by weight, and preferably between 3% and 13% by weight, relative to the total weight of the catalyst, expressed as oxides of Group VIII metals. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO, respectively.

[0049] The content of the group VIB metal is generally between 1% and 30% by weight, preferably between 5% and 20% by weight, and more preferably between 8% and 15% by weight, relative to the total weight of the catalyst, expressed as an oxide of the group VIB metal. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 or WO3, respectively.

[0050] The molar ratio between group VIII metals and group VIB metals is favorably between 0.3 and 3 mol / mol, preferably between 0.4 and 2.5 mol / mol, and very preferably between 0.5 and 2 mol / mol.

[0051] The Group VIII metal is preferably nickel.

[0052] The group VIB metal is preferably molybdenum.

[0053] Preferably, the catalyst does not contain phosphorus.

[0054] Catalysts are typically 50 and 200 m 2 Between / g, preferably 60 and 170m 2 Between / g, preferably 70 and 130m 2 Includes specific surface area between / g

[0055] The pore capacity 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.

[0056] Alumina carrier The alumina support for the catalyst used in the context of a selective hydrogenation process according to the present invention is a macroporous and mesoporous alumina support containing a bimodal distribution of mesopores: The volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 10 volume% and 30 volume% of the total pore volume of the carrier; The volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier; The volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier.

[0057] Preferably, the volume of mesopores in a carrier having a diameter of 2 nm or more and less than 18 nm corresponds to between 15 volume% and 25 volume% of the total pore volume of the carrier.

[0058] Preferably, the volume of mesopores in a carrier having a diameter of 18 nm or more and less than 50 nm corresponds to between 35 volume% and 45 volume% of the total pore volume of the carrier.

[0059] Preferably, the macropore volume of a carrier having a diameter of 50 nm or more and less than 8000 nm corresponds to between 35 volume% and 50 volume% of the total pore volume of the carrier.

[0060] In one embodiment according to the present invention, the pore distribution of mesopores having a diameter of 2 nm or more and less than 18 nm is centered in a range of values ​​between 10.5 and 14.5 nm, preferably between 12 and 13 nm.

[0061] In one embodiment according to the present invention, the pore distribution of mesopores having a diameter of 18 nm or more and less than 50 nm is centered in a range of values ​​between 22 and 28 nm, preferably between 23 and 27 nm.

[0062] The carriers are generally 50 and 210 m 2Between and preferably between 70 and 180 m / g 2 Between and preferably between 70 and 160 m / g 2 It includes the specific surface area between / g.

[0063] The pore volume of the carrier is generally between 0.7 ml / g and 1.3 ml / g, preferably between 0.8 ml / g and 1.2 ml / g.

[0064] Advantageously, the carrier is in the form of beads having a diameter between 0.8 and 10 mm, preferably between 1 and 5 mm, more preferably between 2 and 4 mm.

[0065] Preferably, the catalyst consists of an active phase composed of molybdenum and nickel and a mesoporous and macroporous alumina carrier having a bimodal distribution of mesopores: · The volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 10% and 30% by volume of the total pore volume of the carrier; · The volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 30% and 50% by volume of the total pore volume of the carrier; · The volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 30% and 50% by volume of the total pore volume of the carrier.

[0066] Process for preparing the support The alumina carrier of the catalyst used in the context of the selective hydrogenation process according to the present invention can be synthesized by any method known to those skilled in the art.

[0067] According to a preferred embodiment, the alumina carrier used according to the present invention is in the form of beads. According to this preferred embodiment, the preparation of the carrier includes the following steps: Step s1) of dehydrating aluminum hydroxide or aluminum oxyhydroxide at a temperature between 400 °C and 1200 °C, preferably between 600 °C and 900 °C, for a time between 0.1 second and 5 seconds, preferably between 0.1 second and 4 seconds, to obtain an alumina powder Step s2) The alumina powder obtained in step s1) is formed into the shape of beads. Step s3) Heat-treats the beads obtained in step s2) at a temperature of 200°C or higher. Step s4) involves impregnating the alumina beads obtained at the end of step s3) with water or an aqueous solution, preferably an acidic aqueous solution, and then hydrothermally treating them by retention in an autoclave at temperatures between 100°C and 300°C, preferably between 150°C and 250°C). Step s5) involves calcining the alumina beads obtained at the end of Step s4) at a temperature between 500°C and 820°C.

[0068] Steps s1) through s5) are described in detail below.

[0069] Step 1) According to step s1), aluminum hydroxide or aluminum oxyhydroxide is dehydrated at temperatures between 400°C and 1200°C, preferably between 600°C and 900°C, for a period of 0.1 seconds and 5 seconds, preferably between 0.1 seconds and 4 seconds, to obtain alumina powder. The aluminum hydroxide may be selected from hydraldilite, gibbsite, or bayerite. The aluminum oxyhydroxide may be selected from boehmite or diaspore.

[0070] Preferably, step s1) is carried out by using hydral dilite.

[0071] Generally, step s1) is carried out in the presence of a flow of high-temperature gas, such as dry air or humid air, to allow for the rapid removal and entrainment of evaporated water.

[0072] Generally, the activated alumina powder obtained after dehydration of aluminum hydroxide or oxyhydroxide is ground to a particle size between 10 and 200 μm.

[0073] Generally, the activated alumina powder obtained after dehydration of aluminum hydroxide or oxyhydroxide is washed with water or an acidic aqueous solution. When the washing step is carried out with an acidic aqueous solution, any mineral acid or organic acid may be used, preferably, among mineral acids, nitric acid, hydrochloric acid, perchloric acid, or sulfuric acid, and among organic acids, carboxylic acids (formic acid, acetic acid, or malonic acid), sulfonic acids (p-toluenesulfonic acid), or sulfuric acid esters (sulfuric acid lauryl).

[0074] Step 2) According to Step 2), the alumina powder obtained at the end of Step 1) is molded.

[0075] The alumina powder is molded to obtain beads, which is called granulation and is generally carried out using rotary technology, such as a rotary granulator or rotary drum. This type of process makes it possible to obtain beads with a controlled diameter and pore distribution, which are generally created during the agglomeration step.

[0076] Porosity can be created by various means, such as selecting the particle size distribution of alumina powder or by agglomerating several alumina powders having different particle size distributions. Another method involves mixing the alumina powder with one or more compounds known as pore-forming compounds that disappear by heating and thus create porosity in the beads, before or during the agglomeration step. Examples of pore-forming compounds that can be used include wood flour, charcoal, activated carbon, carbon black, sulfur, tar, polyvinyl chloride, polyvinyl alcohol, naphthalene, or similar plastics or plastic emulsions. The amount of pore-forming compound added is 500 and 1100 kg / m³. 3 During this period, the preferred values ​​are 700 and 950 kg / m³. 3The desired volume for obtaining beads having a compaction density between 0.8 and 10 mm, preferably between 1 and 5 mm, and even more preferably between 2 and 4 mm, is determined by the compaction density and diameter between 0.8 and 10 mm, preferably between 1 and 5 mm, and even more preferably between 2 and 4 mm. The obtained beads can be selected by sieving according to the desired particle size.

[0077] Step 3) In step s3), the alumina powder formed in the form of beads obtained at the end of step s2) is heat-treated at a temperature of 200°C or higher, preferably between 200°C and 1200°C, preferably between 300°C and 900°C, and very preferably between 400°C and 750°C, for a period of generally 1 and 24 hours, preferably between 1 and 6 hours. The beads obtained in this intermediate step are 50 and 420m 2 Between / g, preferably 60 and 350m 2 Between / g, and even more preferably 80 and 300m 2 Includes specific surface area between / g

[0078] Step 4) In step s4), the alumina beads obtained at the end of step s3) are impregnated with water or an aqueous solution, preferably an acidic aqueous solution, and then subjected to hydrothermal treatment by retention in an autoclave at temperatures between 100°C and 300°C, preferably between 150°C and 250°C.

[0079] Hydrothermal treatment is generally carried out at a temperature of 100°C to 300°C, preferably 150°C to 250°C, for a period of more than 45 minutes, preferably 1 to 24 hours, and very preferably 1.5 to 12 hours. Hydrothermal treatment is generally carried out using one or more mineral acids and / or organic acids, preferably nitric acid, hydrochloric acid, perchloric acid, sulfuric acid, or an acidic aqueous solution containing a weak acid having a pH of less than 4, such as acetic acid or formic acid. Generally, the acidic aqueous solution contains one or more compounds that can release anions that can combine with aluminum ions, preferably nitrate ions (e.g., aluminum nitrate), chlorides, sulfuric acid, perchloric acid, chloroacetic acid, trichloroacetic acid, bromoacetic acid, or dibromoacetic acid ions, as well as formic acid and acetic acid with the general formula: R-COO - It also includes compounds containing the anion.

[0080] Step 5) In step s5), the alumina beads obtained at the end of step s4) are sintered at temperatures between 500°C and 820°C, preferably between 550°C and 750°C, for a period of generally 1 and 24 hours, preferably between 1 and 6 hours. At the exit of this step, the resulting alumina beads are 50 and 210 m 2 Between / g, preferably 70 and 180m 2 Between / g, and even more preferably 70 and 160m 2 It has a specific surface area between / g.

[0081] Process for preparing catalysts Catalysts used in the context of selective hydrogenation processes according to the present invention can be prepared by any technique known to those skilled in the art, particularly by impregnation of a selected support with group VIII and VIB elements.

[0082] This impregnation may be carried out, for example, according to a method known to those skilled in the art in the term dry impregnation, in which just the desired amount of the element in the form of a soluble salt in a selected solvent, e.g., deionized water, is introduced so as precisely as possible to fill the porosity of the carrier. The precursors of the active phase based on Group VIII elements and the precursors of the active phase based on Group VIB elements may be introduced simultaneously or sequentially. The impregnation of each precursor may be advantageously carried out at least twice. Thus, the various precursors may be advantageously impregnated sequentially with different impregnation and maturation times. One of the precursors may also be impregnated several times. The carrier thus filled with the solution is left to mature at a temperature below 50°C, preferably at ambient temperature, for periods of 0.5 hours and 12 hours, preferably 0.5 hours and 6 hours, and even more preferably 0.5 hours and 3 hours.

[0083] After introducing the active phase precursor, the catalyst precursor is subjected to an activation treatment. The aim of this treatment is generally to convert the elemental molecular precursor into the oxide phase. In this case, this is oxidation, but simple drying of the catalyst can also be performed.

[0084] In the case of drying, the catalyst precursor is dried at temperatures between 50°C and 200°C, preferably between 70°C and 180°C, for periods typically between 0.5 and 12 hours, and more preferably between 0.5 and 5 hours. The drying step is advantageously carried out on a transverse floor using hot air or any other hot gas. Preferably, when drying is carried out on a transverse floor, the gas used is either air or an inert gas, such as argon or nitrogen. Very preferably, drying is carried out on a transverse floor in the presence of air.

[0085] In the case of oxidation treatment, also known as charring, the treatment is generally carried out in air or dilute oxygen, and the treatment temperature is generally between 200°C and 550°C, preferably between 300°C and 500°C, and advantageously typically for a period between 0.5 and 24 hours, preferably between 0.5 to 12 hours, and even more preferably between 0.5 to 10 hours. The oxidation treatment step is advantageously carried out on a transverse bed using hot air or any other hot gas. Preferably, when the oxidation treatment is carried out on a transverse bed, the gas used is either air or an inert gas, such as argon or nitrogen. Very preferably, the oxidation treatment is carried out on a transverse bed in the presence of air.

[0086] For example, when the group VIII element is nickel and the group VIB element is molybdenum, molybdenum and nickel metal salts that can be used in the catalyst preparation process are, for example, nickel nitrate and ammonium heptamolybdate. Any other salt known to those skilled in the art that is sufficiently soluble and can be decomposed during the activation treatment can also be used. Advantageously, both drying and oxidation treatments are carried out during the catalyst preparation process.

[0087] Prior to its use as a hydrogenation catalyst, it is advantageous to subject the dried or optionally calcined catalyst to a sulfidation step (activation step). This activation step is carried out by methods well known to those skilled in the art, preferably in a sulfur-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. Hydrogen sulfide can be used directly or generated by a sulfide agent (e.g., dimethyl disulfide).

[0088] The catalyst is preferably used in at least partially sulfurized form. The introduction of sulfur may be carried out before or after either activation step, i.e., the drying or calcination step. Sulfur or sulfur compounds may be introduced excitually, i.e., outside the reactor in which the process according to the present invention is carried out, or in situ, i.e., inside the reactor used in the process according to the present invention. In the first case, these excitu sulfurizations are characterized by a final passivation step. In fact, the sulfide phases are very reactive to ambient air (spontaneous exothermic due to oxidation), making their subsequent handling impossible without additional treatment aimed at limiting this reactivity. Among commercially available excitu sulfurization methods, the TOTSUCAT® process from Eurecat (European Patent Nos. 0564317B1 and 0707890B1) and the XpresS® process from Tricat (U.S. Patent No. 5958816A) are mentioned. In the second case (in situ sulfidation), the catalyst is sulfided by passing a feedstock containing at least one sulfur compound, which, once decomposed, leads to the fixation of sulfur on the catalyst. This feedstock may be a gas or a liquid, such as hydrogen containing H2S or a liquid containing at least one sulfur compound.

[0089] Selective hydrogenation process The present invention relates to a process for processing gasoline containing any type of chemical family, particularly diolefins, monoolefins, and sulfur compounds in the form of mercaptans and light sulfides. The present invention finds specific applications in the conversion of gasoline, particularly gasoline derived from catalytic cracking, fluid catalytic cracking (FCC), coking processes, vis-breaking processes, or pyrolysis processes. Preferably, the raw material is gasoline from a catalytic cracking unit. The raw materials to which the present invention is applied generally have boiling points between 0°C and 280°C. The raw materials may also contain hydrocarbons having three or four carbon atoms.

[0090] For example, gasoline from a catalytic cracking (FCC) unit contains, on average, diolefins between 0.5% and 5% by weight, monoolefins between 20% and 50% by weight, and sulfur between 10 ppm and 0.5% by weight, and generally contains less than 300 ppm of mercaptans. Mercaptans are generally concentrated in the light fraction of gasoline, more specifically in fractions with boiling points below 120°C.

[0091] The gasoline treatment described in this selective hydrogenation process is primarily: • Selective hydrogenation of diolefins to monoolefins; • The conversion of light saturated sulfur compounds, mainly mercaptans, into heavier sulfides or mercaptans through reaction with monoolefins; • Isomerizing monoolefin compounds having the C=C double bond in an external position to isomers having the C=C double bond in an internal position. It is located there.

[0092] The hydrogenation reaction from diolefins to monoolefins is illustrated below by the conversion of 1,3-pentadiene, an unstable compound readily hydrogenated to 2-pentene. However, in the example below, it is necessary to limit the side reactions of monoolefin hydrogenation that would lead to the formation of n-pentane.

[0093] [ka]

[0094] The sulfur compounds required for conversion are primarily mercaptans. The main reaction for converting mercaptans consists of thioetherification reactions between monoolefins and mercaptans. This reaction is exemplified below by the addition of propane-2-thiol to 2-pentene to form propylpentyl sulfide.

[0095] [ka]

[0096] In the presence of hydrogen, the conversion of sulfur compounds can also involve the formation of an intermediate H2S molecule. This H2S molecule can then be added to an unsaturated compound present in the starting material. However, this pathway is less common under favorable reaction conditions.

[0097] In addition to mercaptans, compounds that are likely to be converted and made heavier in this manner are sulfides, mainly CS2, COS, thiophans, and methylthiophans.

[0098] In some cases, it is possible to observe reactions that increase the molecular weight of light nitrogen compounds, mainly nitriles, pyrroles, and their derivatives.

[0099] According to the present invention, the catalyst can also carry out isomerization from monoolefin compounds having their C=C double bonds in an external position to their isomers having their C=C double bonds in an internal position.

[0100] This reaction is illustrated below by the isomerization of 1-hexene to 2-hexene or 3-hexene.

[0101] [ka]

[0102] In the selective hydrogenation process according to the present invention, the raw material to be processed is mixed with hydrogen before contact with the catalyst. The amount of hydrogen injected is such that the molar ratio of hydrogen to the diolefin to be hydrogenated is greater than 1 (stoichiometrically) and less than 100, preferably between 1 and 10 mol / mol. Too much hydrogen can lead to strong hydrogenation of the monoolefin, and therefore a decrease in the octane rating of the gasoline. Generally, all of the raw material is injected at the reactor inlet. However, in certain cases, it may be advantageous to inject some or all of the raw material between two consecutive catalyst layers placed in the reactor. This embodiment, in particular, allows the reactor to continue operating even if the reactor inlet becomes clogged with polymer, particle, or gum deposits present in the raw material.

[0103] A mixture of gasoline and hydrogen is heated with a catalyst at a temperature between 80°C and 220°C, preferably between 90°C and 200°C, for 1 hour. -1 and 10h -1 The mixture is brought into contact at a liquid-space velocity (LHSV) between 1 and 2 MPa. The LHSV is the liters of raw material per hour and liters of catalyst per liter of raw material (l / lh). The pressure is adjusted so that the reaction mixture is mostly in liquid form within the reactor. The pressure is between 0.5 MPa and 5 MPa, preferably between 1 and 4 MPa.

[0104] The gasoline processed under the above conditions has reduced content of diolefins and mercaptans. Generally, the resulting gasoline contains less than 1% by weight of diolefins, preferably less than 0.5% by weight. Light sulfur compounds having a boiling point lower than the boiling point of thiophene (84°C) are generally converted in amounts greater than 50%. Thus, it is possible to separate the light fraction from the gasoline by distillation and to send this fraction directly to the gasoline pool without additional hydrodesulfurization treatment. The light fraction of gasoline generally has an endpoint below 120°C, preferably below 100°C, and most preferably below 80°C.

[0105] The selective hydrogenation process according to the present invention is particularly suitable for implementation in the context of the desulfurization process described in European Patent Application No. 1077247.

[0106] The present invention also applies to a process for desulfurizing gasoline containing sulfur compounds, which includes at least the following steps: a) A selective hydrogenation step that implements the process described above; b) Separating the gasoline obtained in step a) into two fractions, one containing light gasoline and the other containing heavy gasoline; c) A step of hydrodesulfurization of the heavy gasoline separated in step b) by catalyst, which enables at least partially the decomposition of sulfur compounds to H2S.

[0107] The separation step b) is preferably carried out by a conventional distillation column, also called a splitter. This fractional distillation column must be capable of separating the light fraction of gasoline containing less than 10 ppm by weight of sulfur.

[0108] This column generally operates at pressures between 0.1 and 2 MPa, preferably between 0.2 and 1 MPa. The theoretical number of stages in this separation column is generally between 10 and 100, preferably between 20 and 60. The reflux ratio, expressed as the ratio of the column's liquid flow rate divided by the distillate flow rate expressed in kg / h, is generally less than 1, preferably less than 0.8.

[0109] The light gasoline obtained at the end of the separation generally contains at least all of the C5 olefins, preferably at least 20% of the C5 compounds and C6 olefins. Generally, this light fraction has a sulfur content of less than 10 ppm by weight. In other words, it is not necessary to treat the light fraction with an additional hydrodesulfurization step before using it as fuel.

[0110] Step c) is preferably a hydrodesulfurization step, which is carried out by passing heavy gasoline over a catalyst containing at least one group VIII element and / or at least one group VIB element in at least partially sulfide form, in the presence of hydrogen, at temperatures between about 210°C and about 350°C, preferably between 220°C and 320°C, and generally at pressures between about 1 and about 4 MPa, preferably between 1.5 and 3 MPa. The liquid space velocity is about 1 and about 20 h -1 Between (expressed as the volume of liquid per unit volume of catalyst and per unit time), preferably 1 and 10 h -1 Between 3 and 8 hours, very preferably. -1 The H2 / raw material ratio is between 100 and 600 Nl / l, with a preference between 300 and 600 Nl / l.

[0111] The content of Group VIII metals expressed as oxides is generally between 0.5% and 15% by weight, and preferably between 1% and 10% by weight, relative to the weight of the catalyst. The content of Group VIB metals expressed as oxides is generally between 1.5% and 60% by weight, and preferably between 3% and 50% by weight, relative to the weight of the catalyst.

[0112] When a group VIII element is present, it is preferably cobalt, and when present, the group VIB element is generally molybdenum or tungsten. A combination such as cobalt-molybdenum is preferred. The catalyst support is usually a porous solid, such as alumina, silica-alumina, or other porous solids, such as magnesia, silica, or titanium oxide, either alone or in a mixture with alumina or silica-alumina. To minimize the hydrogenation of olefins present in heavy gasoline, it is advantageous to preferentially use a catalyst in which the density of the group VIB metal, expressed as weight % of the group VIB metal in oxide form per unit specific surface area (weight %) relative to the total weight of the catalyst, is greater than 0.07, preferably greater than 0.12. The catalyst according to step c) is preferably 250 m 2Less than 230m / g, more preferably 230m 2 Less than / g, very preferably 190m 2 It has a specific surface area of ​​less than / g.

[0113] The metal is supported on a carrier by any method known to those skilled in the art, for example, by dry impregnation, using an excess solution containing the metal precursor. The impregnation solution is selected so as to be able to dissolve the metal precursor at the desired concentration. For example, in the case of the synthesis of a CoMo catalyst, the molybdenum precursor may be molybdenum oxide or ammonium heptamolybdate, and the cobalt precursor may be, for example, cobalt nitrate, cobalt hydroxide, or cobalt carbonate. The precursors are generally dissolved in a medium that allows their solubilization at the desired concentration.

[0114] Following the introduction of one or more elements and optionally the shaping of the catalyst, the catalyst is activated in a first step. This activation may correspond to oxidation and reduction therefrom, or direct reduction, or calcination alone. The calcination step is generally carried out under an airflow at a temperature in the range of about 100°C to about 600°C, preferably between 200°C and 450°C. The reduction step is carried out under conditions that allow at least a portion of the oxidation form of the main component metal to be converted to metal. Generally, this involves treating the catalyst under a hydrogen flow at a temperature preferably equal to at least 300°C. Reduction may also be carried out in part by means of a chemical reducing agent.

[0115] The catalyst used in step c) is preferably used at least partially in its sulfidation form. The introduction of sulfur may be carried out before or after either the activation step, i.e., the calcination or reduction step. Sulfur or sulfur compounds may be introduced excitually, i.e., outside the hydrodesulfurization reactor, or in situ, i.e., inside the hydrodesulfurization reactor. In the first case, these excitu sulfidations are characterized by a final passivation step. In fact, the sulfide phase is very reactive to ambient air (spontaneous exothermic due to oxidation), and without additional treatment aimed at limiting this reactivity, their subsequent handling becomes impossible. Among the commercially available excitu sulfidation methods are the TOTSUCAT® process from Eurecat (European Patent Nos. 0564317B1 and 0707890B1) and the XpresS® process from Tricat (U.S. Patent No. 5958816A). In the second case (in situ sulfidation), the catalyst is preferably reduced under the conditions described above and then sulfided by passing a feedstock containing at least one sulfur compound, which, once decomposed, leads to the fixation of sulfur on the catalyst. This feedstock may be a gas or a liquid, for example, hydrogen containing H2S or a liquid containing at least one sulfur compound. [Examples]

[0116] Example 1: Catalyst A (according to the present invention) The support S1 for catalyst A is obtained by dehydrating hydral dilite (Emplura®, Merck®) to obtain alumina powder. The temperature is set to 800°C, and the contact time of the material to be dehydrated with the dry air stream is 1 second. The obtained alumina powder is pulverized to a particle size between 10 and 200 μm, and then washed three times with distilled water equal to twice the volume of powder used. The alumina powder is then formed in the presence of carbon black (N990Thermax®) using a disc pelletizer (GRELBEX® P30) equipped with a conical cylindrical container at a 30° angle and a rotation speed of 40 rpm, after sieving the solids to obtain beads mainly between 2 and 4 mm in diameter. The amount of carbon black is 800 kg / m³. 3 The beads are adjusted to obtain the compacted powder filling density of the target object. 2 The beads are heat-treated in air at 720°C to give them a specific surface area of ​​1 / g. Next, hydrothermal treatment is applied to the beads by impregnation of the pore capacity with an aqueous solution of nitric acid (0.1N, Merck®). The hydrothermal treatment is carried out in a rotating basket type autoclave at a temperature of 200°C for 6.5 hours. The beads thus obtained are subjected to a final calcination treatment in air at 650°C for 2 hours. The carrier S1 is 141m 2 It has a specific surface area of ​​0.97 ml / g, a total pore volume of 0.97 ml / g, and the following pore distribution as determined by mercury porosimetry: The volume of mesopores with a diameter of 2 nm or more and less than 18 nm, whose pore distribution is concentrated at 13 nm, is 0.15 ml / g, and corresponds to 15% of the total pore volume; The volume of mesopores with a diameter of 18 nm or more and less than 50 nm, whose pore distribution is concentrated at 26 nm, is 0.43 ml / g, and corresponds to 44% of the total pore volume; This represents a macropore volume of 0.39 ml / g with a diameter of 50 nm or more and less than 8000 nm, which corresponds to 40% of the total pore volume.

[0117] The carrier S1 has a water absorption capacity of 0.95 ml / g. The impregnation solution is 6.07 g of ammonium heptamolybdate (Mo7(NH4)6O 24 Catalyst A is prepared by diluting 17.43 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 36.2 ml of distilled water. After a dry impregnation of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The solid is then calcined in air at 450°C for 2 hours. The resulting catalyst A contains 9.1 wt% NiO and 10.0 wt% MoO3, and has a Ni / Mo molar ratio of 1.75. Catalyst A has a total pore capacity of 0.83 ml / g and 103 m 2 It has a specific surface area of ​​ / g.

[0118] Example 2: Catalyst B not according to the present invention (a macroporous and mesoporous catalyst having a unimodal distribution of large mesopores) The support S2 for catalyst B is obtained by dehydration of hydral dilite (Emplura®, Merck) to obtain activated alumina powder. The temperature is set to 800°C, and the contact time of the material to be dehydrated with a stream of dry air is 1 second. The obtained activated alumina powder is ground to a particle size between 10 and 200 μm, and then washed three times with distilled water in a volume equal to twice the volume of powder used. The activated alumina powder is then processed by a disc pelletizer (GRELBEX® P30) equipped with a conical cylindrical container at a 30° angle and a rotation speed of 40 rpm, mainly to a diameter between 2 and 4 mm (after sieving the solid) and at 780 kg / m³. 3 The beads are molded to have a compacted powder filling density of the target material. 2 The beads are heat-treated at 700°C in air to give them a specific surface area of ​​1 / g. Next, hydrothermal treatment is applied to the beads by impregnation of the pore capacity with an aqueous solution of nitric acid (0.1N, Merck®). The hydrothermal treatment is carried out in a rotating basket type autoclave at a temperature of 200°C for 6.5 hours. The beads thus obtained are subjected to a final calcination treatment at 950°C in air for 2 hours. The carrier S2 is 71m2 It has a specific surface area of ​​0.56 ml / g, a total pore volume of 0.56 ml / g, and the following pore distribution as determined by mercury porosimetry: The volume of mesopores with a diameter of 10 nm or more and less than 50 nm, whose pore distribution is concentrated at 20 nm, is 0.35 ml / g, and corresponds to 63% of the total pore volume; This represents a macropore volume of 0.21 ml / g with a diameter of 50 nm or more and less than 8000 nm, which corresponds to 38% of the total pore volume.

[0119] The carrier S2 has a water absorption capacity of 0.54 ml / g. The impregnation solution is 2.76 g of ammonium heptamolybdate (Mo7(NH4)6O 24 ·4H2O, 99.98%, Merck® is prepared by diluting 8.80 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 20.7 ml of distilled water. After a dry impregnation step of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The second impregnation step is performed with 3.18 g of ammonium heptamolybdate (Mo7(NH4)6O 24 The process is carried out with a solution prepared by diluting 7.69 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 18.8 ml of distilled water. After a dry impregnation of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The solid is then calcined in air at 450°C for 2 hours. The resulting catalyst B contains 8.9 wt% NiO and 10.3 wt% MoO3, and has a Ni / Mo molar ratio of 1.67. Catalyst B has a total pore capacity of 0.45 ml / g and 59 m 2 It has a specific surface area of ​​ / g.

[0120] Example 3: Catalyst C (macroporous catalyst) not according to the present invention A commercially available carrier S3 (SA52124, UniSpheres® NorPro) is provided in the form of beads with diameters between 2 and 4 mm. The carrier S3 is 8 m 2 It has a specific surface area of ​​0.33 ml / g, a total pore volume of 0.33 ml / g, and the following pore distribution as determined by mercury porosimetry: This represents the volume of macropores with a diameter of 50 nm or more and less than 8000 nm, which is 0.33 ml / g and corresponds to 100% of the total pore volume.

[0121] The carrier S3 has a water absorption capacity of 0.47 ml / g. The impregnation solution is 2.76 g of ammonium heptamolybdate (Mo7(NH4)6O 24 ·4H2O, 99.98%, Merck® is prepared by diluting 8.80g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 18ml of distilled water. After a dry impregnation step of 40g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The second impregnation step is performed with 3.18g of ammonium heptamolybdate (Mo7(NH4)6O 24 The process is carried out with a solution prepared by diluting 7.69 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 16.4 ml of distilled water. After a dry impregnation of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The solid is then calcined in air at 450°C for 2 hours. Catalyst C contains 8.9 wt% NiO and 10.3 wt% MoO3, and the Ni / Mo molar ratio is 1.68. Catalyst C has a total pore capacity of 0.23 ml / g and 4 m 2 It has a specific surface area of ​​ / g.

[0122] Example 4: Catalyst D (monomodal mesoporous catalyst) that does not conform to the present invention A commercially available carrier S4 (SA6578, NorPro®) is supplied in the form of a 5mm diameter extruded product. Carrier S4 is 175m 2It has a specific surface area of ​​0.82 ml / g, a total pore volume of 0.82 ml / g, and the following pore distribution as determined by mercury porosimetry: The pore volume of mesopores with a diameter of 2 nm or more and 20 nm or less, where the pore distribution is concentrated at 13 nm, is 0.82 ml / g, and corresponds to 100% of the total pore volume.

[0123] The carrier S4 has a water absorption capacity of 0.81 ml / g. The impregnation solution is 6.06 g of ammonium heptamolybdate (Mo7(NH4)6O 24 Catalyst D is prepared by diluting 17.40 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 30.7 ml of distilled water. After a dry impregnation of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The solid is then calcined in air at 450°C for 2 hours. The resulting catalyst D contains 9.0 wt% NiO and 10.0 wt% MoO3, and has a Ni / Mo molar ratio of 1.73. Catalyst D has a total pore capacity of 0.74 ml / g and 127 m 2 It has a specific surface area of ​​ / g.

[0124] Example 5: Catalyst E not according to the present invention (a catalyst having a unimodal distribution of macropores and small mesopores) A commercially available carrier S5 (SA6176, NorPro®) is supplied in the form of an extruded material with a diameter of 1.6 mm. Carrier S5 is supplied in 250 m 2 It has a specific surface area of ​​1.05 ml / g, a total pore volume of 1.05 ml / g, and the following pore distribution as determined by mercury porosimetry: The volume of mesopores having a diameter of 2 nm or more and 20 nm or less, with a pore distribution concentrated at 7 nm, is 0.68 ml / g, and corresponds to 65% of the total pore volume; This represents a macropore volume of 0.37 ml / g with a diameter of 50 nm or more and less than 8000 nm, which corresponds to 35% of the total pore volume.

[0125] The carrier S5 exhibits a water uptake capacity of 1.02 ml / g. The impregnation solution is 6.00 g of ammonium heptamolybdate (Mo7(NH4)6O 24 Catalyst E is prepared by diluting 17.40 g of nickel nitrate (Ni(NO3)2·6H2O, 99.5%, Merck®) with 39.1 ml of distilled water. After a dry impregnation of 40 g of the carrier and a 12-hour maturation step in a humid saturated atmosphere, the solid is dried at 120°C for 12 hours. The solid is then calcined in air at 450°C for 2 hours. Catalyst E contains 9.0 wt% NiO and 9.9 wt% MoO3, and has a Ni / Mo molar ratio of 1.75. Catalyst E has a total pore capacity of 0.84 ml / g and 207 m 2 It has a specific surface area of ​​ / g.

[0126] Example 6: Use of catalyst in selective hydrogenation The activity of catalysts A, B, C, D, and E is evaluated by selective hydrogenation tests of a mixture of model molecules carried out in a 500 ml stirred autoclave reactor. Typically, between 2 and 6 g of catalyst is sulfurized at atmospheric pressure, in a sulfurization bench, under an H2S / H2 mixture consisting of 15 vol% H2S, with 1 l / gh of catalyst and at 400 °C for 2 hours (on a 5 °C / min lamp), followed by a 2-hour plateau under pure hydrogen at 200 °C. This protocol allows for sulfurization rates of over 70% with all catalysts according to the present invention. The thus sulfurized catalyst is transferred to the reactor in the absence of air and then brought into contact with 250 ml of model raw material at a total pressure of 1.5 MPa and a temperature of 160 °C. The pressure is kept constant throughout the test by supplying hydrogen. The raw materials used in the activity test had the following composition: n-heptane, 1000 ppm by weight of sulfur in the form of 3-methylthiophene, 500 ppm by weight of sulfur in the form of mercaptan in the form of 2-propanethol, 10% by weight of olefin in the form of 1-hexene, and 1% by weight of diolefin in the form of isoprene.

[0127] The time t=0 in the test corresponds to the contact between the catalyst and the raw materials. The test length is set to 200 minutes, and gas chromatography analysis of the resulting liquid effluent allows for the evaluation of the activity of various catalysts in the hydrogenation of isoprene (formation of methylbutene), the hydrogenation of 1-hexene (formation of n-hexane), and the increase in molecular weight of 2-propanethol (disappearance of 2-propanethol).

[0128] The catalytic activity for each reaction is defined relative to the normalized rate constant obtained for each reaction per gram of catalyst. The rate constant is calculated assuming a reaction of order 1. The activity is normalized to 100% of catalyst A.

[0129] The selectivity of the catalyst for the hydrogenation of isoprene is equal to the ratio of the catalytic activity of isoprene and 1-hexene in the hydrogenation of isoprene: A(isoprene) / A(1-hexene). The selectivity is normalized to 100% for catalyst A.

[0130] The results obtained using various catalysts are reported in Table 1 below.

[0131] [Table 1]

[0132] It is found that catalyst A according to the present invention has systematically greater diolefin hydrogenation activity and mercaptan molecular weight increase activity than other catalysts. Furthermore, the selectivity is consistently among the highest for catalyst A according to the present invention.

Claims

1. A process for the selective hydrogenation of gasoline containing a polyunsaturated compound and a light sulfur compound, wherein the gasoline and hydrogen are heated with a catalyst at temperatures between 80°C and 220°C for 1 hour. －１ and 10h －１ The catalyst is brought into contact at a liquid space velocity between and a pressure between 0.5 and 5 MPa, having a molar ratio of hydrogen to the diolefin to be hydrogenated greater than 1 and less than 100 mol / mol, wherein the catalyst comprises at least one group VIB metal, at least one group VIII metal, and a mesoporous and macroporous alumina support having a bimodal distribution of mesopores: - The volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 10 volume% and 30 volume% of the total pore volume of the carrier; - The volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier; - The volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 30 volume% and 50 volume% of the total pore volume of the carrier. process.

2. The carrier is 50 and 210 m ２ The process according to claim 1, including the specific surface area between / g.

3. The process according to any one of claims 1 and 2, wherein the carrier has a total pore volume between 0.7 and 1.3 ml / g.

4. The process according to any one of claims 1 to 3, wherein the volume of mesopores having a diameter of 2 nm or more and less than 18 nm corresponds to between 15 volume% and 25 volume% of the total pore volume of the carrier.

5. The process according to any one of claims 1 to 4, wherein the volume of mesopores having a diameter of 18 nm or more and less than 50 nm corresponds to between 35 volume% and 45 volume% of the total pore volume of the carrier.

6. The process according to any one of claims 1 to 5, wherein the volume of macropores having a diameter of 50 nm or more and less than 8000 nm corresponds to between 35 volume% and 50 volume% of the total pore volume of the carrier.

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

8. The process according to claim 7, wherein the content of the group VIII metal in the catalyst, which is expressed in the form of an oxide, is between 1% and 20% by weight relative to the total weight of the catalyst.

9. The process according to any one of claims 1 to 8, wherein the molar ratio of the group VIII metal to the group VIB metal is between 0.3 and 3 mol / mol.

10. The process according to any one of claims 1 to 9, wherein the group VIII metal is nickel.

11. The process according to any one of claims 1 to 10, wherein the VIB group metal is molybdenum.

12. The process according to any one of claims 1 to 11, wherein the pore distribution of the mesopores having a diameter of 2 nm or more and less than 18 nm is centered between 10.5 and 14.5 nm.

13. The process according to any one of claims 1 to 12, wherein the pore distribution of the mesopores having a diameter of 18 nm or more and less than 50 nm is centered between 22 and 28 nm.

14. The process according to any one of claims 1 to 13, wherein the gasoline is catalytic cracking gasoline.

15. The process according to any one of claims 1 to 14, wherein the carrier is in the form of beads having a diameter between 2 and 4 mm.

16. The carrier, Step s1) involves dehydrating aluminum hydroxide or aluminum oxyhydroxide at temperatures between 400°C and 1200°C for times between 0.1 seconds and 5 seconds to obtain alumina powder. Step s2) involves forming the alumina powder obtained in step s1) into the form of beads, Step s3) heat-treats the alumina beads obtained in step s2) at a temperature of 200°C or higher, Step s4) involves hydrothermally treating the alumina beads obtained at the end of step s3) by impregnation with water or an aqueous solution, and then by retention in an autoclave at temperatures between 100°C and 300°C. Step s5) involves calcining the alumina beads obtained at the end of step s4) at a temperature between 500°C and 820°C, The process according to claim 15, obtained in accordance with the above.

17. The process according to any one of claims 1 to 16, wherein the catalyst does not contain phosphorus.

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