Refined hydrodesulfurization catalyst comprising Group VIB metal, Group VIII metal and phosphorus on alpha alumina support

Abstract

A refined hydrodesulfurization catalyst comprising an active phase comprising at least one Group VIB metal and at least one Group VIII metal, phosphorus, and a porous support comprising alpha-alumina. The content of the group VIB metal in the form of oxide is 1-8 wt% relative to the total weight of the catalyst, and the content of the group VIII metal in the form of oxide is 0.2-5 wt% relative to the total weight of the catalyst; and the content of phosphorus in the form of P2O5 thereof is 0.1 wt% to 3 wt% with respect to the total weight of the catalyst, the catalyst having a specific surface area of greater than or equal to 1 m2 / g and less than 20 m2 / g. The catalyst of one example contains oxides of Co, Mo, and P on alpha-alumina.

Description

Field of the Invention

[0001] The present invention relates to the field of hydrotreating gasoline fractions, especially gasoline fractions produced by fluidized bed catalytic cracking units. More particularly, the present invention relates to the use of catalysts in a process for preparing low-sulfur gasoline. The present invention is very particularly applicable to treating gasoline fractions containing olefins and sulfur, such as gasoline produced by catalytic cracking, for which it is desired to reduce the content of sulfur compounds without hydrogenating the olefins and aromatics. Background Art

[0002] Automotive fuel specifications require a significant reduction in the sulfur content of these fuels, especially gasoline. This reduction particularly aims to limit the content of sulfur and nitrogen oxides in motor vehicle exhaust gases. Since 2009, the specifications for gasoline fuels currently in force in Europe have provided for a maximum sulfur content of 10 weight ppm (parts per million). Such specifications are also in force in other countries such as the United States and China, which have required the same maximum sulfur content since January 2017. To meet these specifications, gasoline must be treated via a desulfurization process.

[0003] The main source of sulfur in gasoline base stocks is "cracked" gasoline, and mainly the gasoline fraction of the catalytic cracking process of vacuum distillates obtained from crude oil or atmospheric or vacuum distillation residues. The gasoline fraction from catalytic cracking, which on average accounts for 40% of the gasoline base stock, actually accounts for more than 90% of the sulfur in gasoline. Therefore, the preparation of low-sulfur gasoline requires a desulfurization step for catalytic cracking gasoline. Among the other sources of gasoline that may contain sulfur, mention may also be made of coker gasoline, visbreaking gasoline, or to a lesser extent, gasoline obtained from atmospheric distillation or steam cracking gasoline.

[0004] Removing sulfur from gasoline fractions consists of specifically treating these sulfur-rich gasolines via a desulfurization process in the presence of hydrogen. This is thus called a hydrodesulfurization (HDS) process. However, these gasoline fractions, and more particularly fluid catalytic cracking (FCC) gasoline, contain a large proportion of unsaturated compounds in the form of monoolefins (about 20 wt% to 50 wt%), diolefins (0.5 wt% to 5 wt%) and aromatics that contribute to obtaining a good octane number. These unsaturated compounds are unstable and react during the hydrodesulfurization treatment. Diolefins form gums by polymerization during the hydrodesulfurization treatment. The formation of such gums leads to the progressive deactivation of the hydrodesulfurization catalyst or the progressive clogging of the reactor. Therefore, before any treatment of these gasolines, the diolefins must be removed by hydrogenation. Conventional treatment processes desulfurize gasoline non-selectively by hydrogenating most of the monoolefins, which results in a high loss of octane number and high hydrogen consumption. The latest hydrodesulfurization processes make it possible to desulfurize cracked gasoline rich in monoolefins while limiting the hydrogenation of monoolefins and thus limiting the loss of octane. Such processes are described, for example, in the documents EP-A-1077247 and EP-A-1174485.

[0005] However, when very thorough desulfurization of cracked gasoline is required, a part of the olefins present in the cracked gasoline is hydrogenated on the one hand, and on the other hand recombines with H2S to form mercaptans. Such compounds having the chemical formula R-SH (where R is an alkyl group) are generally referred to as recombined mercaptans and generally account for 20% to 80% by weight of the residual sulfur in the desulfurized gasoline. The reduction of the recombined mercaptan content can be achieved by catalytic hydrodesulfurization, but this results in the hydrogenation of most of the monoolefins present in the gasoline, which in turn leads to a significant reduction in the octane number of the gasoline and excessive consumption of hydrogen. In addition, it is known that the lower the target sulfur content, that is, when attempting to completely remove the sulfur compounds present in the feedstock, the greater the proportionate octane loss due to the hydrogenation of monoolefins during the hydrodesulfurization step.

[0006] The gasoline can thus be treated by a sequence of two reactors as described in document EP 1 077 247; the purpose of the first step (also called the selective HDS step) is generally to carry out deep desulfurization of the gasoline with minimal olefin saturation (and without aromatic loss), thus achieving the maximum octane retention rate. The catalyst used is generally a CoMo-type catalyst. During this step, new sulfur compounds are formed by the recombination of H2S from the desulfurization with the olefins: recombined mercaptans.

[0007] The second step generally serves to minimize the amount of recombined mercaptans. In the second step, the temperature is generally higher in order to thermodynamically promote the removal of the mercaptans. In practice, a furnace is thus placed between the two reactors in order to be able to raise the temperature of the second reactor above that of the first reactor.

[0008] The catalyst used in the refining process must be particularly selective so as not to cause olefin saturation (and without aromatic loss), which would lead to octane loss. Therefore, it must make it possible to reduce the content of total sulfur and mercaptans in the hydrocarbon fraction, preferably the gasoline fraction, to extremely low levels while minimizing the reduction of the octane number. Generally, the catalyst used is based on nickel.

[0009] It is known from patent FR 3,023,184 to provide a hydrotreating catalyst on an alumina-based support, said hydrotreating catalyst comprising at least a Group VIB metal, a Group VIII metal and phosphorus, having a specific surface area of 20 to 150 m 2 / g and 7 to 30 metal atoms / nm 2 High density of the Group VIB metal per unit area of the catalyst of the catalyst.

[0010] It is also known from patent FR 2,840,315 to provide a catalyst comprising at least a Group VIB metal, a Group VIII metal and having a specific surface area of less than 200 m 2Use of a catalyst with a support having a specific surface area of / g, wherein the density of Group VIB metal per unit area of the support is per m 2 Support 4×10 -4 to 36×10 -4 g of Group VIB metal oxide.

[0011] However, there is still a need to maximize the performance of hydrotreated gasoline fractions to meet sulfur specifications.

[0012] Surprisingly, the applicant has found that a catalyst based on at least one Group VIII metal, at least one Group VIB metal, and phosphorus on an α-alumina support can improve gasoline hydrotreating performance when used in a finishing hydrodesulfurization section (FNS) located downstream of a selective hydrodesulfurization section (HDS). Without being bound by any theory, using such a catalyst in the finishing hydrodesulfurization section enables the removal of a portion of refractory sulfur compounds in the finishing section while retaining olefins, which is caused by the high selectivity achieved by the specific interaction between the active phase and the surface of the α-alumina support. Summary of the Invention

[0013] The present invention relates to a finishing hydrodesulfurization catalyst comprising an active phase containing at least one Group VIB metal, at least one Group VIII metal, and phosphorus, and a porous support comprising α-alumina. The content of the Group VIB metal in oxide form is 1 wt% to 8 wt% based on the total weight of the catalyst, the content of the Group VIII metal in oxide form is 0.2 wt% to 5 wt% based on the total weight of the catalyst, and the content of phosphorus in the form of P2O5 is 0.1 wt% to 3 wt% based on the total weight of the catalyst. The catalyst has a specific surface area greater than or equal to 1 m 2 / g and less than 20 m 2 / g.

[0014] According to one or more embodiments, the molar ratio of the Group VIII metal to the Group VIB metal is 0.1 to 2.0 mol / mol.

[0015] According to one or more embodiments, the molar ratio of phosphorus to the Group VIB metal is 0.1 to 2.0 mol / mol.

[0016] According to one or more embodiments, the specific surface area of the catalyst is 1 to 16 m 2 / g.

[0017] According to one or more embodiments, the surface density of the Group VIB metal, expressed as the weight of the Group VIB metal oxide per unit area of the catalyst, is 33×10 -4from 0 to 130×10 -4 g / m 2 。

[0018] According to one or more embodiments, the Group VIII metal is cobalt and the Group VIB metal is molybdenum.

[0019] According to one or more embodiments, the carrier is in the form of beads.

[0020] According to one or more embodiments, the catalyst comprises an active phase composed of molybdenum, cobalt, and phosphorus and a porous support composed of α-alumina. The cobalt content in the form of CoO oxide is 0.5 wt% to 3 wt% relative to the total weight of the catalyst, the molybdenum content in the form of MoO3 oxide is 3 wt% to 7 wt% relative to the total weight of the catalyst, the phosphorus content in the form of P2O5 oxide is 0.3 to 1.5 wt% relative to the total weight of the catalyst, the molar ratio of cobalt to molybdenum is 0.3 to 1.0 mol / mol, the molar ratio of phosphorus to molybdenum is 0.2 to 0.5 mol / mol, and the surface density of molybdenum expressed in the form of MoO3 oxide is 40×10 -4 to 90×10 -4 g / m 2 , and the specific surface area of the catalyst is 1 to 16 m 2 / g.

[0021] Another subject of the present invention relates to a method for treating gasoline containing sulfur compounds and olefins, the method comprising at least the following steps:

[0022] a) In a first reaction section, contacting gasoline, hydrogen, and a hydrodesulfurization catalyst at a temperature of 200°C to 350°C and a pressure of 0.2 MPa to 5 MPa, wherein the space velocity is 1 h -1 to 20 h -1 , and the ratio of the hydrogen flow rate expressed as standard m 3 / h to the flow rate of the feedstock to be treated expressed as m 3 / h under standard conditions is 10 Nm 3 / m 3 to 1000 Nm 3 / m 3 , and the hydrodesulfurization catalyst comprises an active phase and an oxide support, and the active phase comprises a Group VIB metal and a Group VIII metal at least partially in the form of sulfides, thereby obtaining a partially desulfurized effluent;

[0023] b) Without separating the H2S formed in step a), in a second reaction section, the partially desulfurized effluent obtained at the end of step a) is brought into direct contact with the refined hydrodesulfurization catalyst according to the invention, at least partially in the form of a sulfide, at a temperature of 250 °C to 400 °C and a pressure of 0.2 MPa to 5 MPa, with a space velocity of 1 h -1 to 20 h -1 , thereby obtaining a desulfurized effluent.

[0024] According to one or more embodiments, the temperature of step b) is higher than the temperature of step a).

[0025] According to one or more embodiments, the gasoline is catalytic cracking gasoline. Detailed Description

[0026] Definition

[0027] Hereinafter, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIII (or Group VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification.

[0028] The BET specific surface area is measured by nitrogen physisorption according to standard ASTM D3663 - 03, the method being described in the work “Adsorption by Powders & Porous Solids: Principles, Methodology and Applications” by Rouquerol F., Rouquerol J., and Singh K., Academic Press, 1999.

[0029] In the following description of the present invention, the "total pore volume" of an oxide support or a catalyst is understood to mean the volume measured by mercury porosimetry according to standard ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dynes / cm and a contact angle of 140°. The wetting angle is taken as 140° according to the recommendation on page 1050-5 of the publication "Techniques de l'ingénieur, traité analyse et caractérisation" [Techniques of the Engineer, Analysis and Characterization Treatise] written by Jean Charpin and Bernard Rasneur.

[0030] For better precision, the values of the total pore volume given hereinafter in ml / g or in cm 3 / g correspond to the total mercury volume value measured in ml / g or in cm 3 / g on the said sample minus the mercury volume value measured in ml / g or in cm 3 / g on the same sample for a pressure corresponding to 30 psi (about 0.2 MPa).

[0031] The contents of Group VIII metals, Group VIB metals and phosphorus are measured by X-ray fluorescence.

[0032] The contents of Group VIB metals, Group VIII metals and phosphorus in the said catalyst are expressed as oxides after correcting for the loss on ignition of the catalyst sample in a muffle furnace at 550 °C for 2 h. The loss on ignition is due to the loss of moisture. It is determined according to ASTM D7348.

[0033] Refined hydrodesulfurization catalyst

[0034] The catalyst according to the present invention comprises an active phase and a porous support, preferably consisting of an active phase and a porous support. The active phase comprises at least one Group VIB metal and at least one Group VIII metal, phosphorus. The porous support comprises α-alumina, preferably consisting of α-alumina. The content of the Group VIB metal in oxide form is 1 wt% to 8 wt% relative to the total weight of the catalyst. The content of the Group VIII metal in oxide form is 0.2 wt% to 5 wt% relative to the total weight of the catalyst. And the phosphorus content in the form of its P2O5 oxide is 0.1 wt% to 3 wt% relative to the total weight of the catalyst. The catalyst has a pore volume greater than or equal to 1 m 2 / g and less than 20 m2 The specific surface area per g.

[0035] The content of the Group VIB metal in the active phase in oxide form is from 1% to 8% by weight, preferably from 2% to 7% by weight and even more preferably from 3% to 7% by weight relative to the total weight of the catalyst. The Group VIB metal is preferably molybdenum. When the metal is molybdenum, the metal content is expressed as MoO3.

[0036] The content of the Group VIII metal in the active phase in oxide form is from 0.2% to 5% by weight, preferably from 0.5% to 4% by weight and even more preferably from 0.5% to 3% by weight relative to the total weight of the catalyst. The Group VIII metal is preferably cobalt. When the metal is cobalt, the cobalt content is expressed as CoO.

[0037] The content of phosphorus in its P2O5 oxide form is from 0.1% to 3% by weight, preferably from 0.2% to 2% by weight, and even more preferably from 0.3% to 1.5% by weight relative to the total weight of the catalyst.

[0038] Preferably, the molar ratio of the Group VIII metal of the active phase to the Group VIB element of the active phase is from 0.1 to 2.0 mol / mol, preferably from 0.3 to 1.0 mol / mol.

[0039] Preferably, the molar ratio of phosphorus to the Group VIB metal of the active phase is from 0.1 to 2.0 mol / mol, preferably from 0.2 to 1.0 mol / mol, more preferably from 0.2 to 0.5 mol / mol.

[0040] The specific surface area of the catalyst is greater than or equal to 1 m 2 / g and less than 20 m 2 / g, preferably from 1 m 2 / g to 16 m 2 / g, and even more preferably from 5 m 2 / g to 15 m 2 / g.

[0041] The catalyst advantageously has a total pore volume measured by mercury porosimetry of from 0.3 cm 3 / g to 0.9 cm 3 / g, preferably from 0.35 cm 3 / g to 0.8 cm 3 / g, and very preferably from 0.4 cm 3 / g to 0.7 cm 3 / g.

[0042] The surface density of the Group VIB metal expressed as the weight of the Group VIB oxide per unit area of the catalyst is 33×10-4 to 130×10 -4 g / m 2 、preferably 37×10 -4 to 120×10 -4 g / m 2 、more preferably 40×10 -4 to 90×10 -4 g / m 2 。

[0043] Support of the refined hydrodesulfurization catalyst

[0044] The support of the hydrofining hydrodesulfurization catalyst according to the present invention can be in the form of beads, extrudates of any geometric shape, pellets, granules, compressed cylinders, crushed solids or any other shaped body. Preferably, the support is in the form of beads having a diameter of 0.5 to 6 mm, or in the form of cylindrical, trilobal or quadrilobal extrudates having an outside diameter of 0.8 to 3 mm. More preferably, the support is in the form of beads.

[0045] The support of the catalyst according to the present invention contains α-alumina, preferably the support consists mainly of α-alumina, that is, relative to the total weight of the support, it contains at least 51% by weight of α-alumina, preferably at least 60% by weight, very preferably at least 80% by weight, or even at least 90% by weight of α-alumina. Even more preferably, the support consists of α-alumina.

[0046] The specific surface area of the support is greater than or equal to 1 m 2 / g and less than 20 m 2 / g, preferably 1 m 2 / g to 16 m 2 / g, and even more preferably 5 m 2 / g to 15 m 2 / g.

[0047] The support advantageously has a total pore volume measured by mercury porosimetry of 0.3 cm 3 / g to 0.9 cm 3 / g, preferably 0.35 cm 3 / g to 0.8 cm 3 / g, and very preferably 0.4 cm 3 / g to 0.7 cm 3 / g.

[0048] Preparation of the refined hydrodesulfurization catalyst

[0049] The catalyst according to the present invention can be prepared by any technique known to those skilled in the art, in particular by impregnating a metal of Group VIII and a metal of Group VIB and phosphorus on a selected porous support. The impregnation can be carried out, for example, according to a method known to those skilled in the art under the term dry impregnation, in which exactly the required precursor amount of the element in the form of a salt soluble in the selected solvent (such as softened water) is introduced, so as to fill the pores of the support as precisely as possible. Preferably, when the impregnation aqueous solution contains cobalt, molybdenum and phosphorus, the impregnation aqueous solution is prepared under pH conditions that promote the formation of dissolved heteropolyanions. For example, the pH of such an aqueous solution is from 1 to 5. Preferably, the preparation of the catalyst is carried out without adding an organic reagent in admixture with the precursors of the metals of Group VIII and Group VIB and phosphorus.

[0050] For example, in the molybdenum source, oxides and hydroxides, molybdic acid and its salts, especially ammonium salts, such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H3PMo 12 O 40 ) and its salts, and optionally silicomolybdic acid (H4SiMo 12 O 40 ) and its salts can be used. The molybdenum source can also be any heteropoly compound of the Keggin, defective Keggin, substituted Keggin, Dawson, Anderson or Strandberg type, for example. Preferably, molybdenum trioxide and heteropoly compounds of the Keggin, defective Keggin, substituted Keggin and Strandberg types are used.

[0051] The cobalt precursors that can be used are advantageously selected from, for example, oxides, hydroxides, hydroxycarbonates, carbonates and nitrates. Cobalt hydroxide and cobalt carbonate are preferably used.

[0052] Phosphorus can be advantageously introduced alone or in admixture with at least one of the metals of Group VIB and Group VIII. Phosphorus is preferably introduced in admixture with the metal precursors of Group VIB and Group VIII by dry impregnation of the porous support with a solution containing the metal precursor and the phosphorus precursor. The preferred phosphorus source is orthophosphoric acid H3PO4, but its salts and esters, such as ammonium phosphate or mixtures thereof, are also suitable. Phosphorus can also be introduced simultaneously with the Group VIB metal in the form of, for example, a heteropolyanion of the Keggin, defective Keggin, substituted Keggin or Strandberg type.

[0053] The support filled with the solution can be cured at a temperature below 50 °C, preferably at ambient temperature, for a time not exceeding 12 h, preferably not exceeding 6 h.

[0054] After the ripening step, the obtained catalyst precursor can be heat-treated. The purpose of this treatment is usually to convert the molecular precursors of the elements into an oxide phase. In this case, this is an oxidation treatment, but simple drying of the catalyst can also be carried out.

[0055] In the case of drying, the catalyst precursor is dried at a temperature of 50 °C to below 200 °C, preferably 70 °C to 180 °C, for a period of usually 0.5 h to 12 h, and even more preferably for a period of 0.5 h to 5 h.

[0056] In the case of the oxidation treatment (also known as calcination), the treatment is usually carried out in air or in a diluted oxygen carrier, and the treatment temperature is usually 200 °C to 550 °C, preferably 300 °C to 500 °C, and advantageously lasts for a period of usually 0.5 h to 24 h, preferably for a period of 0.5 h to 12 h, and even more preferably for a period of 0.5 h to 10 h.

[0057] Before it is used as a hydrotreating catalyst, it is advantageous to subject the optionally dried or calcined catalyst to a step of activation by sulfidation. This activation stage is carried out by methods known to those skilled in the art and is advantageously carried out in a sulfur-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. Hydrogen sulfide can be used directly or generated from a sulfide reagent such as dimethyldisulfide.

[0058] Method for hydrodesulfurization of gasoline

[0059] Another subject of the present invention relates to a method for treating gasoline containing sulfur compounds and olefins, said method comprising at least the following steps:

[0060] a) In a first reaction section, the gasoline, hydrogen, and a hydrodesulfurization catalyst are contacted at a temperature of 200 °C to 350 °C and a pressure of 0.2 MPa to 5 MPa, where the space velocity is 1 h -1 to 20 h -1 , expressed as the ratio of the hydrogen flow rate in standard m 3 / h to the flow rate of the feedstock to be treated in standard conditions expressed as m 3 / h is 10 Nm 3 / m 3 to 1000 Nm 3 / m 3 , and the hydrodesulfurization catalyst comprises an active phase and an oxide support, and the active phase comprises a Group VIB metal and a Group VIII metal at least partially in the form of sulfides, thereby obtaining a partially desulfurized effluent;

[0061] b) Without separating the H2S formed in step a), in a second reaction section, the partially desulfurized effluent obtained at the end of step a) is brought into direct contact with the hydrodesulfurization catalyst for refining as described above at a temperature of 250 °C to 400 °C and a pressure of 0.2 MPa to 5 MPa, with a space velocity of 1 h -1 to 20 h -1 to obtain a desulfurized effluent.

[0062] Description of the raw materials

[0063] The process according to the invention enables any type of gasoline fraction containing sulfur compounds and olefins, alone or as a mixture, such as fractions from coking, visbreaking, steam cracking or fluid catalytic cracking (FCC) units, to be treated. Such gasoline may optionally consist of a large proportion of gasoline originating from other production processes, such as atmospheric distillation (gasoline from direct distillation (or straight-run gasoline)) or conversion processes (coker or steam cracker gasoline). The feedstock preferably consists of a gasoline fraction produced by a fluid catalytic cracking unit.

[0064] The feedstock is a gasoline fraction containing sulfur compounds and olefins, whose boiling range generally extends from the boiling point of hydrocarbons having 2 or 3 carbon atoms (C2 or C3) to 260 °C, preferably from the boiling point of hydrocarbons having 2 or 3 carbon atoms (C2 or C3) to 220 °C, more preferably from the boiling point of hydrocarbons having 5 carbon atoms to 220 °C. The process according to the invention can also treat feedstocks having an end point lower than those mentioned above, such as, for example, a C5-180 °C fraction.

[0065] The sulfur content of gasoline fractions produced by fluid catalytic cracking (FCC) depends on the sulfur content of the feedstock treated by said FCC, on the presence or absence of pretreatment of the feedstock of said FCC, and on the end point of said fraction. Generally, the sulfur content of the entire gasoline fraction, especially those originating from FCC, is greater than 100 weight ppm, and most of the time greater than 500 weight ppm. For gasoline having an end point greater than 200 °C, the sulfur content is generally greater than 1000 weight ppm; in some cases, they can even reach values of approximately 4000 to 5000 weight ppm.

[0066] The feedstock treated by the process according to the invention can be a feedstock containing sulfur compounds with a sulfur content greater than 200 weight ppm and often greater than 500 ppm.

[0067] In addition, gasoline produced by a fluid catalytic cracking (FCC) unit contains on average 0.5 wt% to 5 wt% of diolefins, 20 wt% to 50 wt% of olefins and 10 weight ppm to 0.5 wt% of sulfur, usually including less than 300 ppm of mercaptans.

[0068] Step a0): Selective hydrogenation step (optional)

[0069] Depending on the type of gasoline to be treated, it may be advantageous to previously treat the aforementioned gasoline in the presence of hydrogen and a selective hydrogenation catalyst in order to at least partially hydrogenate the dienes and to increase the molecular weight of a portion of the light mercaptans (RSH) present in the feed by reaction with olefins to obtain thioethers.

[0070] For this purpose, the gasoline to be treated is sent to a selective hydrogenation catalytic reactor containing at least one fixed or moving bed of a catalyst for the selective hydrogenation of dienes and for increasing the molecular weight of light mercaptans. The reactions for the selective hydrogenation of dienes and for increasing the molecular weight of light mercaptans are preferably carried out on a sulphurized catalyst comprising at least one Group VIII metal and optionally at least one Group VIB metal and an oxide support. The Group VIII metal is preferably chosen from nickel and cobalt, and in particular nickel. The Group VIB metal, when present, is preferably chosen from molybdenum and tungsten, and very preferably molybdenum.

[0071] The oxide support of the catalyst is preferably selected from alumina, nickel aluminate, silicon dioxide, silicon carbide or a mixture of these oxides. Alumina is preferably used, and still more preferably high-purity alumina is used. According to a preferred embodiment, the selective hydrogenation catalyst contains 1% to 12% nickel by weight content of nickel oxide (in the form of NiO) and 6% to 18% molybdenum by weight content of molybdenum oxide (in the form of MoO3), and the nickel / molybdenum molar ratio is 0.3 to 2.5, the metals being deposited on a support consisting of alumina. The degree of sulfidation of the metals constituting the catalyst is preferably greater than 60%.

[0072] During the optional selective hydrogenation step, the reaction mixture is heated to 400 ° C. for 0.5 h at a temperature of 50 ° C. to 250 ° C., preferably 80 ° C. to 220 ° C. and still more preferably 90 ° C. to 200 ° C. -1 Until 20h -1 The gasoline is contacted with the catalyst at an hourly space velocity (HSV) of 1.5 to 2.0, wherein the unit of the hourly space velocity is the volume flow rate (l / l / h) per catalyst bed volume and per hour of feedstock at 15°C. The pressure is 0.2 to 5 MPa, preferably 0.6 to 4 MPa and still more preferably 1 to 3 MPa. The optional selective hydrogenation step is usually carried out at a pressure of 2 to 100 Nm 3 / m 3 , preferably 3 to 30 Nm 3 / m 3 The standard m 3 The hydrogen flow rate is expressed as m / h under standard conditions (15°C, 0.1 MPa). 3 The method is carried out based on the ratio of the volume flow rate of the raw material to be processed to / h.

[0073] After selective hydrogenation, the diolefin content determined via the maleic anhydride value (MAV) according to the UOP 326 method is typically reduced to less than 6 mg maleic anhydride / g, in fact even less than 4 mg MA / g and more preferably less than 2 mg MA / g. In some cases, less than 1 mg MA / g can be obtained.

[0074] The selectively hydrogenated gasoline can then be distilled into at least two fractions, a light fraction and a heavy fraction and optionally an intermediate fraction. In the case of fractionation into two fractions, the heavy fraction is treated according to the process of the invention. In the case of fractionation into three fractions, the intermediate fraction and the heavy fraction can be treated separately according to the process of the invention.

[0075] It should be noted that it is conceivable to simultaneously carry out the hydrogenation of diolefins and the fractionation into two or three fractions by means of a catalytic distillation column, which comprises a distillation column equipped with at least one catalytic bed.

[0076] Step a): Selective hydrodesulfurization (HDS) step

[0077] The hydrodesulfurization step a) is carried out in order to reduce the sulfur content of the gasoline to be treated by converting sulfur compounds into H2S.

[0078] The temperature is generally from 200 °C to 350 °C and preferably from 220 °C to 320 °C. The temperature used must be sufficient to keep the gasoline to be treated in the gas phase in the reactor.

[0079] The operating pressure of this step is generally from 0.2 MPa to 5 MPa and preferably from 1 MPa to 3 MPa.

[0080] The amount of catalyst used in each reactor of the first reaction section is generally such that the volume flow rate ratio (expressed as m 3 of the gasoline to be treated per m of catalyst bed at 15 °C (expressed as m 3 / h) (also known as the space velocity or HSV) is from 1 to 20 h -1 and preferably from 2 to 10 h -1 .

[0081] The hydrogen flow rate is generally such that the ratio of the hydrogen flow rate expressed as standard m 3 / h (Nm 3 / h) to the volume flow rate of the feedstock to be treated expressed as m 3 / h under standard conditions (15 °C, 0.1 MPa) is from 10 to 1000 Nm 3 / m 3 、preferably from 50 to 600 Nm 3 / m 3 . Standard m 3 is understood to mean 1 m at 0 °C and 0.1 MPa3 Volume of the gas.

[0082] The hydrogen required for this step may be fresh hydrogen or recycled hydrogen, preferably free of H2S, or a mixture of fresh hydrogen and recycled hydrogen. Preferably, a mixture of fresh hydrogen and recycled hydrogen will be used.

[0083] Depending on the sulfur content of the feedstock to be treated, the degree of desulfurization in step a) is generally greater than 50% and preferably greater than 70%, such that the product resulting from step a) contains less than 200 weight ppm of sulfur and preferably less than 100 weight ppm of sulfur.

[0084] In the process according to the invention, the degree of hydrogenation of the olefins during this step is preferably less than 50%, more preferably less than 40%.

[0085] According to the invention, as described below, the hydrodesulfurization catalyst of step a) comprises an active phase and an oxide support, the active phase comprising at least one Group VIB metal and at least one Group VIII metal, optionally phosphorus, and preferably consisting of at least one Group VIB metal and at least one Group VIII metal, optionally phosphorus.

[0086] The Group VIB metal present in the active phase of the catalyst is preferably selected from molybdenum and tungsten.

[0087] The Group VIII metal present in the active phase of the catalyst is preferably selected from cobalt, nickel, and mixtures of these two metals.

[0088] The active phase of the catalyst is preferably selected from the group formed by combinations of nickel-molybdenum, cobalt-molybdenum, and nickel-cobalt-molybdenum, and very preferably the active phase consists of cobalt and molybdenum.

[0089] The content of the Group VIII metal, calculated as the oxide of the Group VIII metal, is preferably 0.1% to 10% by weight relative to the total weight of the catalyst, more preferably 0.6% to 8% by weight relative to the total weight of the catalyst, even more preferably 0.6% to 7% by weight, and very preferably 1% to 6% by weight. When the metal is cobalt or nickel, the metal content is expressed as CoO or NiO.

[0090] The content of the Group VIB metal, calculated as the oxide of the Group VIB metal, is preferably 1% to 20% by weight relative to the total weight of the catalyst, more preferably 2% to 18% by weight relative to the total weight of the catalyst, and very preferably 3% to 16% by weight. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 or WO3.

[0091] Preferably, the molar ratio of the Group VIII metal to the Group VIB metal of the catalyst is generally 0.1 to 0.8 mol / mol, preferably 0.2 to 0.6 mol / mol.

[0092] Optionally, relative to the total weight of the catalyst, the catalyst may additionally have a phosphorus content of P2O5 generally of 0.3 wt% to 10 wt%, preferably 0.3 wt% to 5 wt%, very preferably 0.5 wt% to 3 wt%.

[0093] In addition, when phosphorus is present, the phosphorus / (Group VIB metal) molar ratio is generally 0.1 to 0.7 mol / mol, preferably 0.2 to 0.6 mol / mol.

[0094] Preferably, the catalyst of step a) has 60 to 250 m 2 / g, preferably 60 to 200 m 2 / g and even more preferably 65 to 180 m 2 / g, and even more preferably 70 to 130 m 2 / g of specific surface area.

[0095] The total pore volume of the catalyst of step a) is generally 0.3 cm 3 / g to 1.3 cm 3 / g, preferably 0.4 cm 3 / g to 1.1 cm 3 / g.

[0096] The oxide support of the hydrodesulfurization catalyst is generally a porous solid selected from the group consisting of: alumina, silica, silica-alumina, or titanium oxide or magnesia used alone or in combination with alumina or silica-alumina. It is preferably selected from the group consisting of silica, alumina, and silica-alumina. Very preferably, the oxide support consists essentially of alumina, that is, relative to the total weight of the oxide support, it contains at least 51 wt%, preferably at least 60 wt%, very preferably at least 80 wt%, or even at least 90 wt% of alumina. It preferably consists only of alumina.

[0097] In a preferred embodiment, the catalyst of step a) comprises an alumina support and an active phase, the active phase comprising cobalt and molybdenum, preferably consisting of cobalt and molybdenum. The catalyst contains a weight content of cobalt oxide in the form of CoO of 0.1 wt% to 10 wt%, preferably 0.6 wt% to 8 wt%, more preferably 0.6 wt% to 7 wt%, and even more preferably 1 wt% to 6 wt% based on the total weight of the catalyst, and a weight content of molybdenum oxide in the form of MoO3 of 1 wt% to 20 wt%, preferably 2 wt% to 18 wt%, and very preferably 3 wt% to 16 wt% based on the total weight of the catalyst, wherein the cobalt / molybdenum molar ratio is 0.1 to 0.8 mol / mol, preferably 0.2 to 0.6 mol / mol.

[0098] Preferably, the support of the hydrodesulfurization catalyst has a specific surface area of 60 to 250 m 2 / g, preferably 60 to 200 m 2 / g, and even more preferably 65 to 180 m 2 / g, and even more preferably 70 to 130 m 2 / g.

[0099] The total pore volume of the support of the hydrodesulfurization catalyst is generally 0.3 cm 3 / g to 1.3 cm 3 / g, preferably 0.4 cm 3 / g to 1.1 cm 3 / g.

[0100] The support of the hydrodesulfurization catalyst may be in the form of beads, extrudates of any geometric shape, tablets, pellets, compressed cylinders, crushed solids or any other shaped body. Preferably, the support is in the form of beads having a diameter of 0.5 to 6 mm, or in the form of cylindrical, trilobal or quadrilobal extrudates having an outer diameter of 0.8 to 3 mm. More preferably, the support is in the form of beads.

[0101] Subsequently, the first part of the desulfurized effluent obtained at the end of step a) is sent directly to step b) of the process according to the invention without separation.

[0102] Step b): Refined hydrodesulfurization (FNS) step

[0103] During the hydrodesulfurization step a), most of the sulfur compounds are converted to H2S. The remaining sulfur compounds are essentially refractory sulfur compounds, as well as the re-formed mercaptans resulting from the addition of the H2S formed in step a) to the olefins present in the feedstock.

[0104] Step b) of the process according to the invention comprises converting at least a portion of the recombinant mercaptans contained in the first effluent from step a) into olefins and H2S, and converting at least a portion of the sulfur compounds (such as thiophene compounds) contained in the first effluent from step a) into saturated compounds, for example into tetrahydrothiophene (or thiacyclopentane) or into mercaptans, and subsequently at least partially hydrogenolyzing these sulfur compounds to form H2S.

[0105] Preferably, step b) is carried out at a higher temperature than step a). Specifically, by using a higher temperature in this step compared to the temperature of step a), the formation of mercaptans is disadvantaged by changing the thermodynamic equilibrium. Step b) also enables the hydrodesulfurization of residual sulfur compounds to continue.

[0106] The temperature is generally from 250 °C to 400 °C, preferably from 270 °C to 390 °C. The temperature employed must be sufficient to keep the gasoline to be treated in the gas phase in the reactor.

[0107] The operating pressure of this step is generally from 0.2 MPa to 5 MPa and preferably from 1.5 MPa to 3 MPa.

[0108] The amount of catalyst used in each reactor is generally such that the ratio (space velocity or HSV) expressed as the volume flow rate of the gasoline to be treated in m 3 under standard conditions (15 °C, 0.1 MPa) of the catalyst bed, expressed as m 3 / h is from 1 to 20 h -1 and preferably from 2 to 10 h -1 .

[0109] The hydrodesulfurization catalyst as described above is used for the hydrodesulfurization step b).

[0110] In the process according to the invention, during this step, the total olefin hydrogenation degree of step b) is preferably less than 30%, more preferably less than 20%, and very preferably less than 15%.

[0111] Depending on the sulfur content of the feedstock to be treated, the total desulfurization degree of step b) is generally greater than 50% and preferably greater than 70%, such that the product produced by step b) contains less than 50 weight ppm of sulfur and preferably less than 20 weight ppm of sulfur, and even more preferably less than 10 weight ppm of sulfur.

[0112] Step c): Step of separating H2S [optional]

[0113] Separation step c) is carried out to separate the excess hydrogen and the H2S formed during steps a) and b). Any method known to those skilled in the art can be envisaged.

[0114] According to the first embodiment, after steps a) and b), the effluent is cooled to a temperature generally below 80 °C to condense the hydrocarbons. The gas phase and the liquid phase are then separated in a separation drum. The liquid fraction containing the desulfurized gasoline and a portion of the dissolved H2S is sent to a stabilizer column or a debutanizer column. This column separates a top fraction consisting essentially of residual H2S and hydrocarbon compounds having a boiling point lower than or equal to that of butane, and a bottoms fraction, called stabilized gasoline, containing compounds having a boiling point higher than that of normal butane, from which H2S has been removed.

[0115] According to the second embodiment, after the condensation step, the liquid fraction containing the desulfurized gasoline and a portion of the dissolved H2S is sent to a stripping section, while the gas fraction consisting mainly of hydrogen and H2S is sent to a purification section. Stripping can be carried out by heating the hydrocarbon fraction alone or in the presence of injected hydrogen or steam in a distillation column, in order to extract at the top the light compounds entrained by dissolution in the liquid fraction and the dissolved residual H2S. The temperature of the stripped gasoline recovered at the bottom is generally between 120 °C and 250 °C.

[0116] Preferably, the separation step c) is carried out in a stabilizer column or a debutanizer column. This is because the stabilizer column enables a more efficient separation of H2S than the stripping section.

[0117] Step c) is preferably carried out such that the sulfur in the form of residual H2S in the desulfurized gasoline represents less than 30%, preferably less than 20% and more preferably less than 10% of the total sulfur present in the treated hydrocarbon fraction.

[0118] Sulfidation of the catalyst

[0119] Before being contacted with the feedstock to be treated in a hydrodesulfurization process for gasoline, the catalyst used in the process according to the invention generally undergoes a sulfidation step. The sulfidation is preferably carried out in a sulfur-reducing medium, that is to say in the presence of H2S and hydrogen, in order to convert the metal oxides into sulfides. The sulfidation is carried out by injecting into the catalyst a stream containing H2S and hydrogen, or a sulfur compound and hydrogen capable of decomposing into H2S in the presence of the catalyst. Polysulfides, such as dimethyldisulfide (DMDS), are H2S precursors commonly used for sulfiding the catalyst. The sulfur can also originate from the feedstock. The temperature is adjusted so that H2S reacts with the metal oxides to form metal sulfides. This sulfidation can be carried out in situ or ex situ (inside or outside the reactor) of the reactor of the process according to the invention at a temperature between 200 and 600 °C and more preferably between 300 and 500 °C.

[0120] The sulfidation degree of the metals constituting the catalyst is at least equal to 60%, preferably at least equal to 70%. The sulfur content in the sulfided catalyst is measured by elemental analysis according to ASTM D5373. A metal is considered to be sulfided when the overall sulfidation degree defined by the molar ratio of sulfur (S) present on the catalyst to the metal is at least equal to 60% of the theoretical molar ratio corresponding to the complete sulfidation of the relevant metal. The total sulfidation degree is defined by the following equation:

[0121] (S / metal) 催化剂 ≥0.6×(S / metal) 理论

[0122] where:

[0123] (S / metal) 催化剂 is the molar ratio of sulfur (S) present on the catalyst to the metal

[0124] (S / metal) 理论 is the molar ratio of sulfur to the metal corresponding to the complete sulfidation of the metal to obtain a sulfide.

[0125] This theoretical molar ratio varies according to the relevant metal:

[0126] -(S / Co) 理论 = 1

[0127] -(S / Ni) 理论 = 1

[0128] -(S / Mo) 理论 = 2 / 1

[0129] -(S / W) 理论 = 2 / 1

[0130] When the catalyst contains multiple metals, the molar ratio of S present on the catalyst to the combined metals must also be at least equal to 60% of the theoretical molar ratio corresponding to the complete sulfidation of each metal to obtain a sulfide, and this calculation is carried out in proportion to the relative molar fractions of each metal.

[0131] The following examples illustrate the invention without limiting its scope.

[0132] Examples

[0133] The analytical methods used to characterize the feedstock and the effluent are as follows:

[0134] - For sulfur contents above 10 ppm S, the sulfur content according to the ASTM D2622 method, and for sulfur contents below 10 ppm S, the sulfur content according to the ISO 20846 method;

[0135] - Thiol content according to ASTM D3227 method;

[0136] - Olefin content based on gas chromatography analysis according to ASTM D6733 method.

[0137] Example 1: Preparation of catalyst A (according to the present invention)

[0138] Provide support A' mainly composed of α-alumina in the form of beads, which has a particle size of 2 to 4 mm and has a specific surface area of 12 m 2 / g and a pore volume of 0.51 ml / g.

[0139] Subsequently, cobalt, molybdenum, and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (2.56 g, ≥99.5%, Sigma- ) and cobalt hydroxide (0.73 g, 96%, Alfa ) and 85 wt% phosphoric acid (0.49 g, 99.99%, Sigma- ) in 15 ml of softened water at 100 °C. After dry-impregnating 40 g of support A', the impregnated alumina is cured in a water-saturated atmosphere at ambient temperature for 4 h, and then dried at 120 °C for 4 h. The catalyst thus obtained is designated as A.

[0140] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst A is thus as follows: MoO3 = 5.9 ± 0.2 wt%, CoO = 1.3 ± 0.1 wt%, and P2O5 = 0.7 ± 0.1 wt%.

[0141] The Co / Mo and P / Mo molar ratios are 0.39 and 0.24, respectively.

[0142] The specific surface area of catalyst A is 12 m 2 / g. The surface density of molybdenum is 49.2×10 -4 g MoO3 / m 2 .

[0143] Example 2: Preparation of catalyst B (not according to the present invention)

[0144] Provide support B' mainly composed of γ-alumina in the form of beads, which has a particle size of 2 to 4 mm and has a specific surface area of 139 m 2 / g and a pore volume of 0.97 ml / g.

[0145] Subsequently, nickel is added. The impregnation solution is prepared by dissolving nickel nitrate hexahydrate (34.36 g, ≥99.5%, Sigma- ) It is prepared by dry impregnation of 40 g of support B'. After dry impregnation, the impregnated alumina is aged for 4 h in a water-saturated atmosphere at ambient temperature, then dried for 4 h at 120 °C, and finally calcined for 4 h at 450 °C under an air flow of 1 l / h / g. The catalyst thus obtained is designated as B.

[0146] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst B is thus as follows: NiO = 17.9 ± 0.3 wt%.

[0147] The specific surface area of catalyst B is 114 m 2 / g.

[0148] Example 3: Preparation of catalyst C (not according to the present invention)

[0149] Support C' identical to support B' is provided. Cobalt, molybdenum, and phosphorus are then added. The impregnation solution is prepared by dissolving molybdenum oxide (4.62 g, ≥99.5%, Sigma- ) and cobalt hydroxide (1.19 g, 96%, Alfa ) in 28 ml of softened water at 100 °C, and 85 wt% phosphoric acid (1.05 g, 99.99%, Sigma- ). After dry impregnation of 40 g of support C', the impregnated alumina is aged for 4 h in a water-saturated atmosphere at ambient temperature, then dried for 4 h at 120 °C. The catalyst thus obtained is designated as C.

[0150] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst C is thus as follows: MoO3 = 10.0 ± 0.2 wt%, CoO = 2.1 ± 0.1 wt%, and P2O5 = 1.4 ± 0.1 wt%.

[0151] The Co / Mo and P / Mo molar ratios are 0.42 and 0.29, respectively. The specific surface area of catalyst C is 118 m 2 / g.

[0152] The surface density of molybdenum is 8.5×10 -4 g MoO3 / m 2 .

[0153] Example 4: Preparation of catalyst D (not according to the present invention)

[0154] Support D' identical to support B' is provided.

[0155] Cobalt and molybdenum are then added. The impregnation solution is prepared by dissolving ammonium heptamolybdate tetrahydrate (5.64 g, ≥99.5%, Sigma- ) and cobalt(II) nitrate hexahydrate (5.36 g, ≥99.5%, Alfa ) were used for preparation. After dry impregnation of 40 g of support D’, the impregnated alumina was cured for 4 h at ambient temperature in a water-saturated atmosphere, then dried at 120 °C for 4 h, and finally calcined at 450 °C for 4 h under an air flow of 1 l / h / g. The catalyst thus obtained is designated as D.

[0156] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst D is thus as follows: MoO3 = 10.0 ± 0.2 wt% and CoO = 3.0 ± 0.1 wt%.

[0157] The Co / Mo and P / Mo molar ratios are 0.60 and 0, respectively.

[0158] The specific surface area of catalyst D is 124 m 2 / g. The surface density of molybdenum is 8.1×10 -4 g MoO3 / m 2 .

[0159] Example 5: Preparation of catalyst E (not according to the present invention)

[0160] A support E’ mainly composed of γ-alumina in the form of beads was provided, which had a particle size of 2 to 4 mm and a specific surface area of 194 m 2 / g and a pore volume of 0.60 ml / g.

[0161] Cobalt, molybdenum, and phosphorus were then added. The impregnation solution was prepared by dissolving molybdenum trioxide (2.24 g, ≥99.5%, Sigma- ), cobalt(II) hydroxide (0.61 g, 96%, Alfa ), and 85 wt% phosphoric acid (0.49 g, 99.99%, Sigma- ) in 17 ml of softened water at 100 °C. After dry impregnation of 40 g of support E’, the impregnated alumina was cured for 4 h at ambient temperature in a water-saturated atmosphere, then dried at 120 °C for 4 h. The catalyst thus obtained is designated as E.

[0162] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst E is thus as follows: MoO3 = 5.2 ± 0.2 wt%, CoO = 1.1 ± 0.1 wt%, and P2O5 = 0.7 ± 0.1 wt%.

[0163] The Co / Mo and P / Mo molar ratios are 0.42 and 0.27, respectively. The specific surface area of catalyst E is 189 m 2 / g.

[0164] The surface density of molybdenum is 2.7×10 -4 g MoO3 / m 2 。

[0165] Example 6: Preparation of catalyst F (not according to the present invention)

[0166] Provide a support F' mainly composed of δ and θ alumina in the form of cylindrical extrudates with a diameter of 1.6 mm, which has a specific surface area of 78 m 2 / g and a pore volume of 0.84 ml / g.

[0167] Subsequently, cobalt, molybdenum and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (3.67 g, ≥99.5%, Sigma- ), cobalt hydroxide (0.87 g, 96%, Alfa ), 85 wt% phosphoric acid (0.73 g, 99.99%, Sigma- ) in 24 ml of softened water at 100 °C. After dry impregnation of 40 g of support F', the impregnated alumina is cured in a water-saturated atmosphere at ambient temperature for 4 h, and then dried at 120 °C for 4 h. The catalyst thus obtained is designated as F.

[0168] Expressed in oxide form and relative to the weight of the dry catalyst, the final elemental composition of catalyst F is thus as follows: MoO3 = 8.2 ± 0.2 wt%, CoO = 1.5 ± 0.1 wt%, and P2O5 = 1.0 ± 0.1 wt%.

[0169] The Co / Mo and P / Mo molar ratios are 0.36 and 0.25, respectively. The specific surface area of catalyst F is 75 m 2 / g.

[0170] The surface density of molybdenum is 10.9×10 -4 g MoO3 / m 2 。

[0171] Example 7: Use of the catalyst in the gasoline desulfurization process

[0172] Subject the gasoline from the fluid catalytic cracking unit, consisting of 25 wt% olefins and 600 ppm S total sulfur, to a two-step treatment:

[0173] - The first step of selective hydrodesulfurization (HDS) using catalyst D in an adiabatic reactor. The operating conditions for the one-step hydrodesulfurization step of the gasoline feedstock are as follows: HSV = 3 h -1 , P = 2.0 MPa. A pure hydrogen stream is added to the feedstock at the reactor inlet such that H2 / HC = 250 Nm 3 / m 3Send the effluent directly to the reactor of the second step;

[0174] - The second hydrodesulfurization (FNS) step using catalysts A to F in an adiabatic reactor. Only the effluent from the first step is treated in this second step. The operating conditions of the refining step are as follows: HSV = 3 h -1 , P = 2.0 MPa. The reactor inlet temperature is always fixed 35 °C higher than the temperature of the effluent leaving the first selective hydrodesulfurization step.

[0175] Fix the inlet temperature of the reactor entering the first selective hydrodesulfurization step to obtain an effluent with a total sulfur content of 10 weight ppm S (i.e., a total sulfur conversion rate of greater than 98%).

[0176] Before use, the catalysts used in the selective (HDS) and refining (FNS) hydrodesulfurization reactors are sulfided by contacting with a feedstock consisting of sulfur in the form of 2 wt% dimethyldisulfide in n-heptane at a pressure of 3.4 MPa and a temperature of 350 °C for 4 h.

[0177] The properties of the catalysts are given in Table 1. The performance properties in the gasoline desulfurization process are presented in Table 2.

[0178] The results show that compared with using the catalysts known in the prior art, using the catalysts according to the present invention in the refining step of the gasoline hydrodesulfurization process enables the best performance to be obtained, especially in terms of the hydrogenation selectivity of olefins for the same sulfur content specification at the process outlet.

[0179] Table 1

[0180]

[0181] Table 2

[0182]

Claims

1. A refined hydrodesulfurization catalyst, which comprises an active phase containing at least one Group VIB metal, at least one Group VIII metal, and phosphorus, and a porous support containing α-alumina. The content of the Group VIB metal in oxide form is 1 wt% to 8 wt% relative to the total weight of the catalyst, the content of the Group VIII metal in oxide form is 0.2 wt% to 5 wt% relative to the total weight of the catalyst, and the content of phosphorus in the form of P2O5 is 0.1 wt% to 3 wt% relative to the total weight of the catalyst. The catalyst has a specific surface area greater than or equal to 1 m 2 / g and less than 20 m 2 / g.

2. The catalyst according to claim 1, characterized in that, The molar ratio of Group VIII metal to Group VIB metal is from 0.1 to 2.0 mol / mol.

3. The catalyst according to claim 1 or 2, characterized in that, The molar ratio of phosphorus to Group VIB metal is from 0.1 to 2.0 mol / mol.

4. The catalyst according to any one of the preceding claims, characterized in that, The specific surface area of the catalyst is 1 m 2 / g to 16 m 2 / g.

5. The catalyst according to any one of the preceding claims, characterized in that, The surface density of the Group VIB metal, expressed as the weight of the Group VIB metal oxide per unit area of the catalyst, is 33×10 -4 to 130×10 -4 g / m 2 .

6. The catalyst according to any one of the preceding claims, characterized in that, The Group VIII metal is cobalt and the Group VIB metal is molybdenum.

7. The catalyst according to any one of the preceding claims, characterized in that, The carrier is in the form of beads.

8. The catalyst according to any one of the preceding claims, which comprises an active phase composed of molybdenum, cobalt and phosphorus and a porous support composed of α-alumina, the cobalt content in the form of CoO oxide is 0.5 wt% to 3 wt% relative to the total weight of the catalyst, the molybdenum content in the form of MoO3 oxide is 3 wt% to 7 wt% relative to the total weight of the catalyst, the phosphorus content in the form of P2O5 oxide is 0.3 wt% to 1.5 wt% relative to the total weight of the catalyst, the molar ratio of cobalt to molybdenum is 0.3 to 1.0 mol / mol, the molar ratio of phosphorus to molybdenum is 0.2 to 0.5 mol / mol, and the surface density of molybdenum expressed in the form of MoO3 oxide is 40×10 -4 to 90×10 -4 g / m 2 , the specific surface area of the catalyst is 1 to 16 m 2 / g.

9. A method for treating gasoline containing sulfur compounds and olefins, said method comprising at least the following steps: a) In the first reaction section, gasoline, hydrogen, and a hydrodesulfurization catalyst are contacted at a temperature of 200°C to 350°C and a pressure of 0.2 MPa to 5 MPa, where the space velocity is 1 h -1 to 20 h -1 , expressed as the ratio of the hydrogen flow rate in standard m 3 / h to the volume flow rate of the feedstock to be treated in standard conditions expressed as m 3 / h is 10 Nm 3 / m 3 to 1000 Nm 3 / m 3 , and the hydrodesulfurization catalyst comprises an active phase and an oxide support, and the active phase comprises a Group VIB metal and a Group VIII metal at least partially in the form of sulfides, thereby obtaining a partially desulfurized effluent; b) Without separating the H2S formed in step a), in a second reaction section, the partially desulfurized effluent obtained at the end of step a) is brought into direct contact with the refined hydrodesulfurization catalyst according to any one of claims 1 to 8, at least partially in the form of a sulfide, at a temperature of 250 °C to 400 °C and a pressure of 0.2 MPa to 5 MPa, with a space velocity of 1 h -1 to 20 h -1 , thereby obtaining a desulfurized effluent.

10. The method according to claim 9, wherein the catalyst in step a) comprises an alumina carrier and an active phase comprising cobalt and molybdenum, said catalyst containing from 0.1 wt% to 10 wt% of the weight content of cobalt oxide in the form of CoO relative to the total weight of the catalyst, from 1 wt% to 20 wt% of the weight content of molybdenum oxide in the form of MoO3 relative to the total weight of the catalyst, wherein the cobalt / molybdenum molar ratio is from 0.1 to 0.8 mol / mol.

11. The method according to claim 9 or 10, wherein the catalyst in step a) has a specific surface area of 60 to 250 m 2 / g.

12. The method according to any one of claims 9 to 11, wherein the temperature in step b) is higher than the temperature in step a).

13. The method according to any one of claims 9 to 12, wherein the gasoline is catalytically cracked gasoline.

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