Hydrodesulfurization catalyst with active phase distribution as crust

Abstract

To provide a catalyst for hydrodesulfurization of a sulfur-containing olefinic gasoline fraction which exhibits an equal or better activity and selectivity than previously, and to provide a hydrodesulfurization method.SOLUTION: A catalyst comprises: an active phase which contains at least one group VIB element, at least one group VIII element and phosphorus; and a support containing alumina. At least 80 wt.% of the group VIB elements, the group VIII elements and the phosphorus are distributed in the form of a crust at the periphery of the support and the thickness of the crust is between 100 and 1200 μm. The content of group VIB element is between 1 wt.% and 8 wt.%, the content of group VIII element is between 0.5 wt.% and 5 wt.%, and the content of phosphorus is between 0.2 wt.% and 3 wt.% relative to the total weight of the catalyst, and the support has a specific surface area of between 100 m2 / g and 250 m2 / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the field of hydrogenation treatment of gasoline fractions, particularly gasoline fractions derived from fluidized bed catalytic cracking units. More specifically, the present invention relates to a catalyst and a method for hydrodesulfurization of sulfur-containing olefinic gasoline fractions, such as gasoline derived from catalytic cracking, sought to reduce the content of sulfur-bearing compounds without hydrogenating olefins and aromatic compounds. [Background technology]

[0002] Petroleum refining and petrochemicals are now subject to new constraints. This is because all countries are gradually adopting stricter sulfur specifications, the aim of achieving, for example, 10 ppm (by weight) of sulfur in petroleum sold in Europe and Japan. The problem of reducing sulfur content essentially focuses on gasoline obtained by cracking the main sulfur precursors in the gasoline pool, whether catalytically (FCC: Fluid Catalytic cracking) or non-catalytically (coking, bisque cracking, steam cracking).

[0003] One solution for reducing sulfur content, well known to those skilled in the art, involves hydrotreating (or hydrodesulfurizing) hydrocarbon fractions (particularly catalytic cracking gasoline) in the presence of hydrogen and a heterogeneous catalyst. However, this method has a major drawback: if the catalyst employed is not sufficiently selective, it causes a very significant drop in octane number. This drop in octane number is linked, in particular, to the hydrogenation of olefins present in this type of gasoline accompanying hydrodesulfurization. Unlike other hydrotreating methods, hydrodesulfurization of gasoline must therefore be able to respond to two conflicting constraints: providing extreme hydrodesulfurization of gasoline and limiting the hydrogenation of any unsaturated compounds present.

[0004] One way to address this dual problem consists of employing a hydrodesulfurization catalyst that is active from the perspective of hydrodesulfurization and highly selective for hydrodesulfurization relative to the hydrogenation reaction of olefins.

[0005] In this context, B. Liu et al. demonstrated an improvement in the performance level of the hydrodesulfurization of gasoline derived from a catalytic cracking process using a CoMoS catalyst on gamma-alumina when the CoMoS phase is distributed as a crust within the catalyst (Non-Patent Documents 1 and 2).

[0006] Furthermore, the literature (Patent Document 1) discloses a selective hydrogenation catalyst for FCC gasoline, which contains nickel and molybdenum deposited on an alumina support, and nickel and molybdenum are distributed in the form of a crust around the support.

[0007] The literature (Patent Document 2) discloses a hydrothermal cracking method using a catalyst based on nickel, cobalt, and molybdenum, which are distributed in the form of a crust around the support.

[0008] Finally, the literature (Patent Document 3) discloses a catalyst composed of an active phase based on Mo, V, W, Cu, and the active phase is placed around the single body. This catalyst can advantageously be used to convert acrolein to acrylic acid.

[0009] In this context, one goal of the present invention is to provide its use in a method for the hydrodesulfurization of a sulfur-containing olefinic gasoline fraction that exhibits performance levels of activity and selectivity that are at least as good as, and even better than, those of catalysts known from the prior art.

Prior Art Documents

Patent Documents

[0010] [Patent Document 1] Chinese Patent Application Publication No. 104275191 Specification [Patent Document 2] U.S. Patent Application Publication No. 2018 / 0193823 [Patent Document 3] U.S. Patent Application Publication No. 2011 / 275856 [Non-patent literature]

[0011] [Non-Patent Document 1] B. Liu et al., “Fuel”, 2012, Volume 25, p.457-463 [Non-Patent Document 2] B. Liu et al., “JOURNAL OF NATURAL GAS CHEMISTRY”, Volume 21, published March 2, 2012, p.194-199 [Overview of the Initiative] [Means for solving the problem]

[0012] (Subject of the invention) The present invention relates to a catalyst comprising an active phase containing at least one group VIB element, at least one group VIII element, and phosphorus, and a porous support containing at least alumina, wherein at least 80% by weight of the group VIB elements, group VIII elements, and phosphorus are distributed around the support in the form of a crust, the thickness of the crust being 100 to 1200 μm, the content of the group VIB elements being 1% to 8% by weight relative to the total weight of the catalyst as measured in oxide form, the content of the group VIII elements being 0.5% to 5% by weight relative to the total weight of the catalyst as measured in oxide form, the content of phosphorus being 0.2% to 3% by weight relative to the total weight of the catalyst as measured in its oxide form P2O5, and the specific surface area of ​​the support being 100 m². 2 / g~250m 2 This relates to a catalyst characterized by being / g.

[0013] The applicant has surprisingly discovered that catalysts based on at least one group VIII element, at least one group VIB element, and phosphorus, particularly distributed within a support having a specific specific surface area, exhibit better hydrogenodesulfurization activity and better hydrogenodesulfurization selectivity compared to catalysts disclosed in the prior art. Without wishing to connect them by any theory, it is assumed that the hydrogenation of sulfur-containing compounds is limited by the diffusion of reagents within the support; therefore, improved activity and selectivity in selective hydrogenation are permissible due to the active phase predominantly present around the support. This is because the combination of phosphorus with group VIII and group VIB elements allows for control of the interaction between the active phase and the alumina-based support, which has a high specific surface area that promotes the localization of the active phase as a crust, while simultaneously maintaining a high dispersion that maximizes the number of active sites and promotes the conversion of sulfur-containing compounds. By optimizing the active phase on a specific support, it becomes possible to use catalysts with less packing of the active phase, while simultaneously achieving performance levels in terms of activity and / or selectivity that are equivalent to, or even better than, those obtained with conventional catalysts.

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

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

[0016] According to one or more embodiments, the specific surface area of ​​the carrier is 120 to 220 m². 2 It is / g.

[0017] According to one or more embodiments, the thickness of the crust is 200 to 1000 μm.

[0018] According to one or more embodiments, the content of element VIB is measured in oxide form and is 2% to 7% by weight relative to the total weight of the catalyst.

[0019] According to one or more embodiments, the content of Group VIII elements is measured in oxide form and is 0.5% to 4% by weight relative to the total weight of the catalyst.

[0020] According to one or more embodiments, the phosphorus content is measured in its oxide form P2O5 and is 0.2% to 2% by weight relative to the total weight of the catalyst.

[0021] According to one or more embodiments, the carrier is based on gamma-alumina and / or chi-alumina, which are used alone or in mixtures.

[0022] According to one or more embodiments, the carrier is in the form of beads.

[0023] According to one or more embodiments, the molar ratio of Group VIII elements to Group VIB elements is 0.35 to 0.45 mol / mol.

[0024] According to one or more embodiments, the molar ratio of phosphorus to group VI metals is 0.2 to 0.4 mol / mol.

[0025] According to one or more embodiments, the specific surface area of ​​the carrier is 130 m². 2 / g~198m 2 It is / g.

[0026] According to one or more embodiments, the total pore volume of the carrier is measured by mercury porosimetry and is 0.3 to 0.9 cm³. 3 It is / g.

[0027] Another subject matter according to the present invention is a method for hydrodesulfurization of a sulfur-containing olefinic gasoline fraction, which comprises contacting the gasoline fraction, hydrogen and the catalyst according to the present invention, and the temperature during the hydrodesulfurization process is 200°C to 400°C, the total pressure is 1 MPa to 3 MPa, and the hourly space velocity is defined as the volume flow rate of the feedstock relative to the volume of the catalyst, and is 1 h -1 ~10 h -1 and the volume ratio of hydrogen / gasoline fraction is 100 to 600 SL / L.

Embodiments for Carrying out the Invention

[0028] (Detailed Description of the Invention) (Definitions) In the following description of this specification, the groups of chemical elements are given by the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor-in-chief D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIII according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IUPAC classification.

[0029] The term "specific surface area" means the BET specific surface area (S BET (m 2 / g)) determined by nitrogen adsorption according to the standard ASTM D 3663 - 78 established from the Brunauer - Emmett - Teller method described in the periodical "The Journal of the American Chemical Society", 1938, 60, 309.

[0030] The total pore volume of the catalyst or the support used for the preparation of the catalyst means the volume measured, for example, by a Micromeritics® instrument, model Autopore III, by mercury porosimetry intrusion according to the standard ASTM D4284 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dynes / cm and a contact angle of 140°.

[0031] The wetting angle was considered equal to 140°, following the recommendation of Jean Charpin and Bernard Rasneur in the publication “Techniques de l'ingenieur, traite analyze et caracterisation” [Techniques of the Engineer, Analysis and Characterization Treatise: Papers on the Techniques, Analysis and Characterization of Engineers], pages 1050-1055. For greater accuracy, the total pore volume value corresponds to the difference between the total pore volume value measured by mercury intrusion porosimetry on the sample and the total pore volume value measured by mercury intrusion porosimetry on the same sample at a pressure corresponding to 30 psi (approximately 0.2 MPa).

[0032] The content of Group VIII elements, Group VIB elements, and phosphorus is measured by X-ray fluorescence.

[0033] (Definition of the coefficient R of the distribution) The elemental distribution profile within the catalyst granules is obtained using a Castan microprobe. At least 30 analyses are performed at a rate of approximately 10 points along the diameter of the bead or extruder, or at points on the crust of the active elements (in this case, elements of groups VIB and VIII and phosphorus), and at approximately 10 points or at the center of the granule. The distribution profile c(x)(x ≤ [-r; +r]) is therefore obtained by the local weight concentration c of the element, the radius r of the bead or extruder, and the position x of the analysis point along the diameter of this granule relative to the center of the granule.

[0034] The distribution of elements is characterized by a dimensionless coefficient R of the distribution, which weights the local concentration by increasing mass as a function of position on the diameter. By definition, this is as follows:

[0035]

number

[0036] Therefore, elements with uniform concentration have a distribution coefficient R equal to 1, elements deposited as a dome (concentration higher at the core than at the edges of the carrier) have a coefficient greater than 1, and elements distributed as a crust (concentration higher at the edges than at the core of the carrier) have a coefficient less than 1. Analysis using a Castan microprobe gives the concentration values ​​for a finite number of x values, and R is therefore numerically evaluated by integral methods well known to those skilled in the art. Preferably, R is determined by the trapezoidal rule.

[0037] (Definition of crust thickness for elements of Groups VIB and VIII and phosphorus) To analyze the distribution of the active phases of Group VIB elements, Group VIII elements, and phosphorus within the support, the crust thickness is measured using a Castan microprobe (or electron microprobe trace analysis). The device used is the CAMECA® XS100, which features four monochromator quartz crystals enabling simultaneous analysis of the four elements. The Castan microprobe analysis technique consists of detecting X-rays emitted by the solid after excitation of the elements in the solid with a high-energy electron beam. For the application of this characterization, catalyst particles are coated within blocks of epoxy resin. These blocks are polished to a cross-section through the diameter of the beads or extruders, and then metallized by depositing carbon in a metal evaporator. The electron probe is scanned along the diameter of five beads or extruders to obtain an average distribution profile of the constituent elements of the solid.

[0038] If the analyzed elements are distributed as a crust, their local concentration generally decreases gradually when measured starting from the edge of the catalyst grain and moving inward. To measure the crust thickness, which is significant for most of the group VIB and group VIII elements and phosphorus particles, the crust thickness is defined as the distance to the edge of the grain containing 80% by weight of all group VIB and VIII elements and phosphorus.

[0039] This is defined in the publication “Measurement of palladium crust thickness on catalyst by EPMA”, Materials Science and Engineering 32 (2012) by L. Sorbier et al. To measure crust thickness, which is significant for most particles, crust thickness can alternatively be defined as the distance to the edge of a grain containing 80 wt% of all group VIB elements, group VIII elements, and phosphorus. From the distribution profile (c(x)) obtained using a Castan microprobe, the cumulative amount Q(y) of each element in the grain can be calculated as a function of the distance y to the edge of a grain of radius r.

[0040] About the bead:

[0041]

number

[0042] About extruded materials:

[0043]

number

[0044] During the ceremony, r: radius of the particle; y: distance to the edge of the particle; x: Integral variable (position on the profile).

[0045] The concentration profile is assumed to result from the diameter taken from x = -r^+r (where x = 0 is the center).

[0046] Q(r) therefore corresponds to the total amount of elements in the grain. The following equation can be solved numerically for y.

[0047]

number

[0048] c is a strictly positive function, and Q is therefore a strictly increasing function, and this equation has a single solution which is the crust thickness.

[0049] (catalyst) The catalyst according to the present invention comprises, preferably, an active phase containing at least one group VIB element, at least one group VIII element, and phosphorus, and a porous support containing at least alumina, wherein at least 80% by weight of the group VIB elements, group VIII elements, and phosphorus are distributed around the support in the form of a crust, the thickness of the crust is 100 to 1200 μm, the content of the group VIB elements is measured in the form of oxides and is 1% to 8% by weight relative to the total weight of the catalyst, the content of the group VIII elements is measured in the form of oxides and is 0.5% to 5% by weight relative to the total weight of the catalyst, the content of phosphorus is measured in the form of its oxide P2O5 and is 0.2% to 3% by weight relative to the total weight of the catalyst, and the specific surface area contained in the support is 100 m². 2 / g~250m 2 It is characterized by being / g.

[0050] Advantageously, the elements of groups VIB and VIII, as well as phosphorus, are distributed around the porous support, and the distribution coefficient R, measured using a Castan microprobe, is less than 0.8, preferably less than 0.7.

[0051] Advantageously, at least 80% by weight of elements from groups VIB and VIII and phosphorus are distributed in a crust around the carrier, and the thickness of the crust is 100 to 1200 μm, preferably 200 to 1000 μm.

[0052] The content of the group VIB element in the active phase is measured in oxide form and is 1% to 8% by weight, preferably 2% to 7% by weight, and more preferably 3% to 6% by weight, relative to the total weight of the catalyst. The group VIB element is preferably selected from molybdenum and tungsten. More preferably, the group VIB element is molybdenum. When the element is molybdenum or tungsten, the metal content is expressed as MoO3 or WO3, respectively.

[0053] The content of the Group VIII element in the active phase is measured in oxide form and is 0.5% to 5% by weight, preferably 0.5% to 4% by weight, and more preferably 0.5% to 3% by weight, relative to the total weight of the catalyst. The Group VIII element is preferably selected from nickel, cobalt, and iron. More preferably, the Group VIII element is cobalt. When the element is cobalt or nickel, the elemental content is expressed as CoO or NiO, respectively.

[0054] The phosphorus content is measured in its oxide form P2O5 and is 0.2% to 3% by weight, preferably 0.2% to 2% by weight, and more preferably 0.3% to 1.5% by weight, relative to the total weight of the catalyst.

[0055] The content of Group VIB elements, Group VIII elements, and phosphorus in the catalyst is expressed as the corrected oxide for the ignition loss of the catalyst sample at 550°C for 2 hours in a muffle furnace. The ignition loss is due to moisture loss and is determined according to ASTM D7348.

[0056] Preferably, the molar ratio of the group VIII element in the active phase to the group VIB element in the active phase is 0.1 to 2.0 mol / mol, preferably 0.3 to 1.0 mol / mol, more preferably 0.3 to 0.5 mol / mol, and even more preferably 0.35 to 0.45 mol / mol.

[0057] Preferably, the molar ratio of phosphorus to the group VIB elements in the active phase is 0.1 to 2.0 mol / mol, preferably 0.2 to 1.0 mol / mol, more preferably 0.2 to 0.7 mol / mol, even more preferably 0.2 to 0.5 mol / mol, and even more preferably 0.2 to 0.4 mol / mol.

[0058] The specific surface area of ​​the catalyst is 100 m². 2 / g~250m 2 / g, preferably 120m 2 / g~220m 2 / g, more preferably 120m 2 / g~200m 2 / g, 130m is preferred over the first layer. 2 / g~198m 2 It is / g.

[0059] The total pore volume of the catalyst was measured by mercury porosimetry and was favorably 0.3 cm³. 3 / g~0.9cm 3 / g, preferably 0.35cm 3 / g~0.8cm 3 / g, very preferably 0.4cm 3 / g~0.7cm 3 It is / g.

[0060] (carrier) The catalyst support according to the present invention may be in the form of beads, extruded material of any geometric shape, platelets, pellets, compressed cylinders, other crushed solids, or any other shape. Preferably, the support is in the form of beads having a diameter of 0.5 to 6 mm or in the form of cylindrical, trilobed, or tetralobed extruded material having a circumscribed diameter of 0.8 to 3 mm. More preferably, the support is in the form of beads.

[0061] The support for the catalyst according to the present invention comprises alumina, preferably selected from the following aluminas: gamma-, delta-, theta-, eta-, rhoe-, chi-, and kappa-alumina, and used alone or in mixtures. Preferably, the support is based on gamma-alumina and / or chi-alumina, which are used alone or in mixtures.

[0062] The specific surface area of ​​the carrier is 100 m². 2 / g~250m 2 / g, preferably 120m 2 / g~220m 2 / g, more preferably 120m 2 / g~200m 2 / g, 130m is preferred over the first layer. 2 / g~198m 2 It is / g.

[0063] The total pore volume of the carrier was measured by mercury porosimetry and was favorably 0.3 cm³. 3 / g~0.9cm 3 / g, preferably 0.35cm 3 / g~0.8cm 3 / g, very preferably 0.4cm 3 / g~0.7cm 3 It is / g.

[0064] (Preparation of catalyst) The catalyst according to the present invention can be prepared by any technique known to those skilled in the art, in particular by impregnation of Group VIII and Group VIB elements and phosphorus onto a selected porous carrier. The impregnation may be carried out, for example, by a method known to those skilled in the art under the term dry impregnation, in which just an amount of a precursor of the desired element in the form of a salt soluble in a selected solvent, e.g., demineralized water, is introduced so as accurately as possible to fill the porous portions of the carrier. Preferably, the impregnation aqueous solution is prepared under pH conditions that promote the formation of heteropolyanions in the solution, if it contains cobalt, molybdenum, and phosphorus. For example, the pH of such an aqueous solution is 1 to 5. Preferably, the preparation of the catalyst is carried out without the addition of an organic agent as a mixture with the Group VIII and Group VI elements and the phosphorus precursor.

[0065] Examples of substances that may be used include molybdenum, its oxides and hydroxides, molybdic acid and its salts, in particular ammonium salts, such as ammonium molybdate, ammonium heptamolybdate, and phosphomolybdic acid (H3PMo). 12 O 40 ), and its salts, and silicic acid (H4SiMo 12 O 40 ) and its salts are found in the sources. The source of molybdenum can be any heteropoly compound of the type of Keggin, lacnary Keggin, substituted Keggin, Dawson, Anderson, or Strandberg. Preferably used are molybdenum trioxide and heteropoly compounds of the type of Keggin, lacnary Keggin, substituted Keggin, and Strandberg.

[0066] The tungsten precursors that can be used are also well known to those skilled in the art. For example, tungsten, oxides and hydroxides, tungstic acid and its salts, in particular ammonium salts, such as ammonium tungstate or ammonium metatungstate, phosphotungstic acid and its salts, and optionally tungstosilicic acid (H4SiW) 12 O 40) and its salts are found in the sources. The source of tungsten can be any heteropoly compound of the type of Keggin, lacunary Keggin, substituted Keggin, or Dawson. Preferably used are oxides and ammonium salts, such as ammonium metatungstate, or heteropolyanions of the type of Keggin, lacunary Keggin, or substituted Keggin.

[0067] 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 preferred for use.

[0068] The nickel precursors that can be used are advantageously selected from, for example, oxides, hydroxides, hydroxycarbonates, and nitrates. Nickel hydroxide and nickel hydroxycarbonate are preferred for use.

[0069] Phosphorus can be introduced advantageously, either alone or as a mixture with at least one element from Group VIB and Group VIII. Preferably, phosphorus is introduced by dry impregnation of the porous carrier using a solution containing precursors of the elements and a phosphorus precursor, as a mixture with precursors of metals from Group VIB and Group VIII. A suitable source of phosphorus is orthophosphate (H3PO4), but its salts and esters, such as ammonium phosphate or mixtures thereof, are also suitable for use. Phosphorus can also be introduced simultaneously with one or more elements from Group VIB, for example, in the form of heteropolyanions of the type of Keggin, lachnary Keggin, substitutional Keggin, or Strandberg.

[0070] The support, thus filled with the solution, is allowed to mature at a temperature below 50°C, preferably at ambient temperature, for a period not exceeding 12 hours, preferably not exceeding 6 hours.

[0071] Following the maturation process, the resulting catalyst precursor can be subjected to heat treatment. The purpose of this treatment is generally to convert the elemental molecular precursor into an oxide phase. In this case, this is oxidation, but simple drying of the catalyst may also be performed.

[0072] In the case of drying, the catalyst precursor is dried at a temperature of 50°C to 200°C, preferably 70°C to 180°C, typically over a period of 0.5 hours to 12 hours, and more preferably over a period of 0.5 hours to 5 hours.

[0073] In the case of oxidation treatment, also known as calcination, the treatment is generally carried out under air or diluted oxygen, the treatment temperature is generally 200°C to 550°C, preferably 300°C to 500°C, and the advantageous duration is typically 0.5 hours to 24 hours, preferably 0.5 hours to 12 hours, and more preferably 0.5 hours to 10 hours.

[0074] Before being used as a hydrogenation catalyst, it is advantageous to subject the catalyst, which may be dried or calcined, to a sulfidation activation step. This activation phase is carried out by methods well known to those skilled in the art, preferably in a sulfo-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).

[0075] (Method for hydrodesulfurization of gasoline) The hydrogenation process involves contacting a sulfur-containing olefinic gasoline fraction with the catalyst and hydrogen described above under the following conditions: - Temperature: 200°C to 400°C, preferably 230°C to 330°C; - Total pressure: 1 MPa to 3 MPa, preferably 1.5 MPa to 2.5 MPa; - Hourly space velocity (HSV): Defined as the volumetric flow rate of the feed material relative to the volume of the catalyst, 1h -1 ~10h -1 Preferably 2h -1~6h -1 ; - Volume ratio of hydrogen / gasoline supply material: 100-600 SL / L, preferably 200-400 SL / L.

[0076] Therefore, the method according to the present invention makes it possible to process all types of sulfur-containing olefinic gasoline fractions, such as fractions derived from coking, bisque breaking, steam cracking, or catalytic cracking (FCC) units. This gasoline may, in some cases, consist of a significant proportion of gasoline that may originate from other production methods, such as atmospheric distillation (gasoline derived from direct distillation (or straight-run gasoline)) or conversion methods (gasoline after coking or steam cracking). The feedstock preferably consists of a gasoline fraction derived from a catalytic cracking unit.

[0077] The raw materials are preferably gasoline fractions containing sulfur-containing compounds and olefins, and having a boiling point between 30°C and less than 250°C, preferably 35°C to 240°C, and more preferably 40°C to 220°C.

[0078] The sulfur content of gasoline fractions produced by catalytic cracking (FCC) depends on the sulfur content of the feedstock processed by the FCC, the presence or absence of pretreatment of the feedstock to the FCC, and also on the endpoint of the fraction. Generally, the overall sulfur content of gasoline fractions, particularly those originating from FCC, is over 100 ppm by weight, and in most cases, over 500 ppm by weight. For gasoline with endpoints above 200°C, the sulfur content is often over 1000 ppm by weight; in given cases, it can even reach values ​​of around 4000-5000 ppm by weight.

[0079] In addition, gasoline derived from catalytic cracking (FCC) units contains, on average, 0.5% to 5% by weight of diolefins, 20% to 50% by weight of olefins, and 10 ppm to 0.5% by weight of sulfur, with less than 300 ppm of sulfur generally being thiols. Thiols are generally concentrated in the lighter fractions of gasoline, more specifically in the fractions whose boiling point is below 120°C.

[0080] It should be noted that sulfur compounds present in gasoline may also include heterocyclic sulfur compounds, such as thiophenes, alkylthiophenes, or benzothiophenes. Unlike thiols, these heterocyclic compounds cannot be removed by extraction methods. These sulfur compounds are consequently removed by hydrogenation, which leads to their conversion to hydrocarbons and H2S.

[0081] Preferably, the gasoline processed by the method according to the present invention is heavy gasoline HCN derived from a distillation step aimed at separating a broad fraction of gasoline (or FRCN for Full Range Cracked Naphtha) derived from a cracking method into light gasoline (LCN for Light Cracked Naphtha) and heavy gasoline (or HCN for Heavy Cracked Naphtha). The cut points for the light and heavy gasoline are determined so as to limit the sulfur content of the light gasoline and to allow it to be used in the gasoline pool, preferably without further post-treatment. Advantageously, the broad fraction FRCN is subjected to a selective hydrogenation step described below prior to the distillation step.

[0082] (Examples) The present invention will now be described through the following examples, but this does not limit the scope of the present invention.

[0083] (Example 1: Preparation of Catalyst A (compliant with the present invention)) A carrier A' is provided. This carrier is mainly composed of gamma-alumina in bead form with a particle size of 2-4 mm and has a specific surface area of ​​194 m². 2 It has a pore volume of 0.60 mL / g and a pore volume of 0.60 mL / g.

[0084] Next, cobalt, molybdenum, and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (1.14 g, ≥99.5%, Sigma-Aldrich®), cobalt hydroxide (0.3 g, 96%, Alfa Aesar®), and 85% by weight phosphoric acid (0.24 g, 99.99%, Sigma-Aldrich®)) in 16 mL of demineralized water at 100°C. After dry impregnation of 20 g of support A', the impregnated alumina is allowed to mature in a water-saturated atmosphere at ambient temperature for 4 hours, and then dried at 120°C for 4 hours. The catalyst thus obtained is denoted as A.

[0085] The final metal composition of catalyst A, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 5.3 ± 0.2 wt%, CoO = 1.1 ± 0.1 wt%, and P2O5 = 0.7 ± 0.1 wt%. The molar ratios of Co / Mo and P / Mo are 0.39 and 0.27, respectively. The pore volume of catalyst A is 0.55 mL / g, and the specific surface area is 189 m². 2 It is / g.

[0086] The elemental distribution and crust thickness in the active phase of catalyst A were measured using a castan microprobe and are shown in Table 1.

[0087] (Example 2: Preparation of Catalyst B (compliant with the present invention)) A carrier B' is provided. This carrier is mainly composed of gamma-alumina in the form of beads with a particle size of 2-4 mm and a specific surface area of ​​145 m². 2 It has a pore volume of 0.63 mL / g and a pore volume of 0.63 mL / g.

[0088] Next, cobalt, molybdenum, and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (1.12 g, ≥99.5%, Sigma-Aldrich®), cobalt hydroxide (0.3 g, 96%, Alfa Aesar®), and 85% by weight phosphoric acid (0.24 g, 99.99%, Sigma-Aldrich®)) in 14.7 mL of demineralized water at 100°C. After dry impregnation of 20 g of support B', the impregnated alumina is allowed to mature in a water-saturated atmosphere at ambient temperature for 4 hours, and then dried at 120°C for 4 hours. The catalyst thus obtained is denoted as B.

[0089] The final metal composition of catalyst B, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 5.2 ± 0.2 wt%, CoO = 1.1 ± 0.1 wt%, and P2O5 = 0.7 ± 0.1 wt%. The molar ratios of Co / Mo and P / Mo are 0.38 and 0.26, respectively. The pore volume of catalyst B is 0.57 mL / g, and the specific surface area is 141 m². 2 It is / g.

[0090] The elemental distribution and crust thickness in the active phase of catalyst B were measured using a Castan microprobe and are shown in Table 1.

[0091] (Example 3: Catalyst C (not conforming to the present invention; low S) BET (Preparation of) A carrier C' is provided. This carrier is mainly composed of theta- and delta-alumina in bead form with a particle size of 2-4 mm and has a specific surface area of ​​81 m². 2 It has a pore volume of 1.03 mL / g and a pore volume of 1.03 mL / g.

[0092] Next, cobalt, molybdenum, and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (0.63 g, ≥99.5%, Sigma-Aldrich®), cobalt hydroxide (0.16 g, 96%, Alfa Aesar®), and 85% by weight phosphoric acid (0.14 g, 99.99%, Sigma-Aldrich®)) in 14.8 mL of demineralized water at 100°C. After dry impregnation of 20 g of support C', the impregnated alumina is allowed to mature in a water-saturated atmosphere at ambient temperature for 4 hours, and then dried at 120°C for 4 hours. The catalyst thus obtained is denoted by C.

[0093] The final metal composition of catalyst C, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 3.0 ± 0.2 wt%, CoO = 0.6 ± 0.1 wt%, and P2O5 = 0.4 ± 0.1 wt%. The molar ratios of Co / Mo and P / Mo are 0.38 and 0.27, respectively. The pore volume of catalyst C is 1.02 mL / g, and the specific surface area is 80 m². 2 It is / g.

[0094] The elemental distribution and crust thickness in the active phase of catalyst C were measured using a Castan microprobe and are shown in Table 1.

[0095] (Example 4: Preparation of Catalyst D (not conforming to the present invention, phosphorus-free)) A carrier D' is provided. This carrier is identical to carrier A' in Example 1.

[0096] Next, cobalt and molybdenum are added. The impregnation solution is prepared by dissolving ammonium heptamolybdate tetrahydrate (1.39 g, 99.98%, Sigma-Aldrich®) and cobalt nitrate hexahydrate (0.89 g, 98%, Sigma-Aldrich®)) in 16 mL of water at 90°C. After dry impregnation of 20 g of support D', the impregnated alumina is allowed to mature in a water-saturated atmosphere at ambient temperature for 4 hours, and then dried at 120°C for 4 hours. The solid is then calcined in air at 450°C for 2 hours. The catalyst thus obtained is denoted as D.

[0097] The final metal composition of catalyst D, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 5.3 ± 0.2 wt% and CoO = 1.1 ± 0.1 wt%. The molar ratio of Co / Mo is 0.39. The pore volume of catalyst D is 0.58 mL / g, and the specific surface area is 182 m². 2 It is / g.

[0098] The elemental distribution and crust thickness in the active phase of catalyst D were measured using a Castan microprobe and are shown in Table 1.

[0099] (Example 5: Preparation of Catalyst E (not conforming to the present invention, high Mo content)) A carrier E' is provided. This carrier is identical to carrier B' in Example 2.

[0100] Next, cobalt, molybdenum, and phosphorus are added. The impregnation solution is prepared by dissolving molybdenum oxide (2.45 g, ≥99.5%, Sigma-Aldrich®), cobalt hydroxide (0.60 g, 96%, Alfa Aesar®), and 85% by weight phosphoric acid (0.53 g, 99.99%, Sigma-Aldrich®)) in 14.7 mL of demineralized water at 90°C. After dry impregnation of 20 g of support E', the impregnated alumina is allowed to mature in a water-saturated atmosphere at ambient temperature for 4 hours, and then dried at 120°C for 4 hours. The catalyst thus obtained is denoted as E.

[0101] The final metal composition of catalyst E, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 10.5 ± 0.2 wt%, CoO = 2.0 ± 0.1 wt%, and P2O5 = 1.4 ± 0.1 wt%. The molar ratios of Co / Mo and P / Mo are 0.37 and 0.27, respectively. The pore volume of catalyst E is 0.52 mL / g, and the specific surface area is 136 m². 2 It is / g.

[0102] The elemental distribution and crust thickness in the active phase of catalyst E were measured using a Castan microprobe and are shown in Table 1.

[0103] (Example 6: Catalyst F (not conforming to the present invention, high S) BET (Preparation without phosphorus) A carrier F' is provided. This carrier is mainly composed of gamma-alumina in bead form with a particle size of 2-4 mm and has a specific surface area of ​​264 m². 2 It has a pore volume of 0.46 mL / g and a pore volume of 0.46 mL / g.

[0104] The catalyst was prepared on 28 g of support F' according to the procedure provided in the experimental section of the paper Journal of Natural Gas Chemistry 21 (2012) 194-199, the amount of impregnation solution was adjusted to the pore volume of the support F' used, and the impregnation time was set to 15 minutes.

[0105] Catalyst F is obtained. The final elemental composition of catalyst F, expressed in oxide form relative to the weight of the dry catalyst, is as follows: MoO3 = 6.8 ± 0.2 wt% and CoO = 1.8 ± 0.1 wt%. The molar ratio of Co / Mo is 0.57. The specific surface area of ​​catalyst F is 242 m². 2 The pore volume is 0.44 mL / g.

[0106] The elemental distribution and crust thickness in the active phase of catalyst F were measured using a Castan microprobe and are shown in Table 1.

[0107] (Example 7: Evaluation of the performance levels of catalysts A to F used in hydrodesulfurization) In this embodiment, the performance levels of catalysts A to F are evaluated in the hydrodesulfurization of catalytically cracked gasoline.

[0108] A typical model feedstock for catalytic cracking (FCC) gasoline contains 10% by weight of 2,3-dimethylbuta-2-ene and 0.33% by weight of 3-methylthiophene (i.e., 1000 ppm by weight of sulfur in the feedstock), and this feedstock is used to evaluate the catalytic performance quality of various catalysts. The solvent used is heptane.

[0109] Hydrodesulfurization (HDS) was carried out in a transverse fixed-bed reactor at 210°C, with HSV = 6h, under a total pressure of 1.5 MPa, in the presence of 4 mL of catalyst. -1 The reaction is carried out with HSV (Heat Stability Value = Volumetric Flow Rate of Feed / Volume of Catalyst) and an H2 / Federation Volume Ratio of 300 SL / L. Prior to the HDS reaction, the catalyst is sulfurized in situ at atmospheric pressure under a flow of hydrogen containing 15 mol% H2S at 350°C for 2 hours.

[0110] Each catalyst is placed in the reactor in sequence. Samples are taken at different time intervals and analyzed by gas chromatography to observe the disappearance of reagents and the formation of products.

[0111] The catalytic performance quality of catalysts is evaluated from the viewpoints of catalytic activity and selectivity. Hydrodesulfurization (HDS) activity is expressed from the rate constant (kHDS) for the HDS reaction of 3-methylthiophene, normalized by the volume of the introduced catalyst, and first-order kinetics are assumed for sulfur compounds. Hydrogenation activity of olefins (HydO) is expressed from the rate constant for the hydrogenation reaction of 2,3-dimethylbuta-2-ene, normalized by the volume of the introduced catalyst, and first-order kinetics are assumed for olefins.

[0112] Catalyst selectivity is expressed by the normalized ratio of rate constants kHDS / kHydO. The kHDS / kHydO ratio increases as the catalyst becomes more selective. The obtained value is normalized by considering catalyst A as the reference (relative HDS activity and relative selectivity equal to 100). The performance level is therefore relative HDS activity and relative selectivity.

[0113] [Table 1]

[0114] Catalysts A and B according to the present invention exhibit better performance levels in terms of activity and selectivity, while simultaneously enabling better efficiency of the active phase. Therefore, it should be noted that small amounts of elements from groups VIB and VIII are used.

Claims

1. A catalyst comprising an active phase containing at least one Group VIB element, at least one Group VIII element and phosphorus, and a porous support containing at least alumina, wherein at least 80% by weight of the Group VIB element, Group VIII element and phosphorus are distributed in the form of a crust around the support, the thickness of the crust is 100 to 1200 μm, the content of the Group VIB element is measured in the form of an oxide and is 1% to 8% by weight relative to the total weight of the catalyst, the content of the Group VIII element is measured in the form of an oxide and is 0.5% to 5% by weight relative to the total weight of the catalyst, the content of phosphorus is measured in the form of its oxide P2O5 and is 0.2% to 3% by weight relative to the total weight of the catalyst, and the specific surface area of the support is 100 m ２ / g to 250 m ２ / g.

2. The catalyst according to claim 1, wherein the molar ratio of the Group VIII element to the Group VIB element is 0.1 to 2.0 mol / mol.

3. The catalyst according to claim 1, wherein the molar ratio of phosphorus to the Group VIB metal is 0.1 to 2.0 mol / mol.

4. The specific surface area of the carrier is 120 m ２ / g to 220 m ２ / g, and the catalyst according to claim 1 is characterized by this.

5. The catalyst according to claim 1, wherein the thickness of the crust is 200 to 1000 μm.

6. The catalyst according to claim 1, wherein the content of the Group VIB element, measured in the form of an oxide, is 2 wt% to 7 wt% relative to the total weight of the catalyst.

7. The catalyst according to claim 1, wherein the content of the Group VIII element, measured in the form of an oxide, is 0.5 wt% to 4 wt% relative to the total weight of the catalyst.

8. The catalyst according to claim 1, wherein the content of phosphorus, measured in the form of its oxide P2O5, is 0.2 wt% to 2 wt% relative to the total weight of the catalyst.

9. The catalyst according to claim 1, wherein the carrier is based on gamma-alumina and / or kai-alumina, which are used alone or as a mixture.

10. The catalyst according to claim 1, wherein the carrier is in the form of beads.

11. The catalyst according to claim 1, wherein the molar ratio of the Group VIII element to the Group VIB element is 0.35 to 0.45 mol / mol.

12. The catalyst according to claim 1, wherein the molar ratio of phosphorus to the Group VIB metal is 0.2 to 0.4 mol / mol.

13. The specific surface area of the carrier is 130 m ２ / g to 198 m ２ / g, and the catalyst according to claim 1 is characterized in that.

14. The total pore volume of the carrier is measured by mercury porosimetry and is 0.3 cm ３ / g to 0.9 cm ３ / g, and the catalyst according to claim 1 is characterized in that.

15. A method for the hydrodesulfurization of a sulfur-containing olefinic gasoline fraction, comprising contacting the gasoline fraction, hydrogen, and the catalyst according to any one of claims 1 to 14, wherein the temperature during the hydrodesulfurization process is 200°C to 400°C, the total pressure is 1 MPa to 3 MPa, and the hourly space velocity is defined as the volumetric flow rate of the feedstock relative to the volume of the catalyst and is 1 h －１ to 10 h －１ and the volume ratio of hydrogen to gasoline fraction is 100 to 600 SL / L.