Hydrotreating process employing a sequence of catalysts with a catalyst based on nickel, molybdenum and tungsten

Abstract

The present invention relates to a method for hydrotreating a hydrocarbon feedstock with a distillation temperature range between 150°C and 600°C to obtain a hydrotreated effluent. The method comprises the following stages: a) contacting the hydrocarbon feedstock with at least one first catalyst in the presence of hydrogen, the first catalyst occupying a volume V1 and comprising a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel and molybdenum; b) contacting the effluent obtained in stage a) with at least one second catalyst in the presence of hydrogen, the second catalyst occupying a volume V2 and comprising a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel, molybdenum, tungsten, and phosphorus, wherein the volume distributions V1 / V2 are between 50 vol% / 50 vol% and 90 vol% / 10 vol%, respectively.

Description

Technical Field

[0001] This invention relates to a method for hydrogenating hydrocarbon feedstocks using at least two catalyst sequences, wherein the second catalyst is based on nickel, molybdenum, and tungsten. The object of this invention is to produce feedstocks that have undergone hydrodesulfurization, hydrodenitrogenation, and / or hydrodearomatics treatment. Prior Technology

[0002] Conventional hydrotreating catalysts generally comprise an oxide support and an active phase based on a metal from Group VIb and VIII in its equivalent oxide form and also based on phosphorus. The preparation of such catalysts generally involves an impregnation stage of the metal and phosphorus onto the support, followed by drying and calcination to obtain the active phase in its equivalent oxide form. Before being used in hydrotreating and / or hydrocracking reactions, these catalysts are generally subjected to sulfidation to form the active entity.

[0003] Those skilled in this technique have suggested adding organic compounds to hydrotreating catalysts to improve their activity, especially for catalysts prepared by impregnation followed by drying without subsequent calcination. Such catalysts are commonly referred to as "additive-impregnated dry catalysts".

[0004] Typically, catalysts used for hydrotreating hydrocarbon fractions are designed to sequentially remove sulfur-based, nitrogen-based, or aromatic compounds (e.g.) from them so that the petroleum products meet the specifications (sulfur content, aromatic content, and the like) required for a given application (motor vehicle fuel, gasoline or gas oil, household fuel oil, jet fuel).

[0005] As many countries strengthen their legislation regarding air quality, there is ongoing effort to develop more effective catalysts and methods for producing ultra-low sulfur fuels (especially diesel (ULSD)). While significant progress has been made in developing highly efficient catalysts for these methods, major challenges remain, such as achieving adequate aromatic saturation activity. Since recent environmental restrictions have established minimum cetane numbers and lower limits for polyaromatic content in diesel fractions, improving the aromatic saturation activity of hydrotreating catalysts has become a key research focus.

[0006] In the pretreatment field of hydrocracking or fluidized bed catalytic cracking (or FCC) methods, it is also necessary to reduce the content of sulfur, nitrogen, and especially aromatics to improve the performance and quality in subsequent hydrocracking or FCC stages. These methods generally process feedstocks rich in sulfur, nitrogen, and aromatics.

[0007] However, hydrotreating catalysts optimized for hydrodesulfurization (HDS) are not automatically optimized for aromatic saturation (or hydrodearomatization (HDA)) or hydrodenitrogenation (HDN), and vice versa. Therefore, it is usually necessary to resort to catalyst sequences, where each catalyst is optimized for a specific type of hydrotreating.

[0008] These supported catalyst sequences (for example) are described in documents US2011 / 0079542, US 5 068 025, CN1176290, FR 3 013 720 or FR 3 013 721.

[0009] There are also unsupported catalyst sequences, also known as "bulk" catalysts, and are known, for example, from US 7 816 299 or CN102851070. However, supported catalyst sequences show the advantage of using renewable catalysts, which are also cheaper (because they contain less metal charge) and are active even with low metal content.

[0010] Document US2003 / 0116473 discloses a hydrogenation process using a molybdenum-based supported catalyst followed by a tungsten-based supported catalyst sequence. This document does not disclose the volume distribution of the two catalytic regions.

[0011] Document CN105435824 discloses a hydrogenation method using a citric acid-supported CoMoP catalyst followed by a citric acid-supported NiMoWP catalyst sequence. The volume of the first catalyst is between 5% and 95%, and the volume of the second catalyst is between 95% and 5%. An increase in HDS and HDN was observed.

[0012] Regardless of the catalyst sequence chosen, induced modification cannot consistently improve the performance of catalytic systems to meet specifications regarding the sulfur, nitrogen, and / or aromatics content of fuels. Therefore, it is crucial for refiners to discover novel hydrotreating methods with improved performance in terms of activity and stability.

[0013] The applicant company has developed a method for hydrogenating hydrocarbon feedstocks, which involves contacting the feedstock with a specific catalyst sequence to increase the overall activity and overall stability of the method. Summary of the Invention

[0014] This invention relates to a method for hydrotreating hydrocarbon feedstocks with a distillation range between 150°C and 600°C at temperatures between 180°C and 450°C, pressures between 0.5 and 30 MPa, space velocity between 0.1 and 20 h⁻¹, and hydrogen / feed ratios between 50 l / l and 5000 l / l, to obtain a hydrotreated effluent. The hydrogen / feed ratio is expressed as the volume of hydrogen measured under standard temperature and pressure conditions per volume of liquid feedstock. The method includes the following stages: a) A first hydrotreating stage is carried out in a first hydrotreating reaction section using at least one catalyst bed comprising at least one first hydrotreating catalyst. The hydrotreating reaction section is fed by at least the hydrocarbon feedstock and a hydrogen-containing gas stream. The first catalyst comprises a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel and molybdenum. b) A second hydrotreating stage is carried out in a second hydrotreating reaction section using at least one catalyst bed comprising at least one second hydrotreating catalyst. This hydrotreating reaction section is fed with at least a portion of the effluent obtained in stage a). The second catalyst comprises a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel, molybdenum, tungsten, and phosphorus. The first hydrogenation reaction section containing the first catalyst occupies a volume V1, and the second hydrogenation reaction section containing the second catalyst occupies a volume V2. The volume V1 / V2 distribution is between 50% / 50% and 90% / 10% of the first and second hydrogenation reaction sections, respectively.

[0015] Unexpectedly, the applicant company has discovered that the sequence of a first hydrotreating reaction section containing a first catalyst based on an active phase composed of nickel and molybdenum and a second hydrotreating reaction section containing a second catalyst based on an active phase composed of nickel, molybdenum and tungsten exhibits a synergistic effect in terms of activity and stability in hydrotreating, particularly in aromatics hydrogenation (HDA), but also in hydrodesulfurization (HDS) and / or hydrodenitrogenation (HDN), in the presence of phosphorus. When a certain distribution is observed in the respective volumes of the first and second hydrotreating reaction sections, particularly between 50 vol% / 50 vol% and 90 vol% / 10 vol% of the first and second hydrotreating reaction sections, respectively.

[0016] This is because the first bimetallic catalyst, based on the active phase composed of nickel and molybdenum, carries out a portion of HDS and HDN, and then the second trimetallic catalyst, based on the active phase composed of nickel, molybdenum and tungsten, carries out HDA and HDN in a certain ratio in the presence of phosphorus, thereby obtaining a highly active and stable catalytic sequence to achieve the specified hydrocarbon fraction.

[0017] On the one hand, the second catalyst exhibits very high activity, particularly in HDA and HDN, which allows it to supplement the hydrotreating (especially HDS and HDN) reactions of the first catalyst necessary to achieve the required specifications. Typically, due to this increased activity, the temperature required to achieve the desired sulfur, nitrogen, or aromatic content (e.g., in the case of gas oil feedstock, under ULSD or ultra-low sulfur diesel mode, a maximum sulfur content of 10 ppm, or polyaromatic content < 8 wt% and cetane number > 46 (summer) and 43 to 46 (winter)) can be reduced. Similarly, stability increases due to the reduced required temperature and extended cycle time.

[0018] On the other hand, compared to bimetallic catalysts, trimetallic catalysts deactivate more slowly, which allows for increased cycle time for standard feedstocks or enables the processing of feedstocks rich in sulfur, nitrogen and / or aromatics.

[0019] The volume distribution of the two catalysts, particularly the fact that the second reaction section containing the second catalyst occupies a smaller volume than the first reaction section containing the first catalyst, allows for the optimization of the HDS, HDN, and HDA reactions carried out in the first or second reaction section to obtain hydrocarbon fractions of the required specifications. At the same time, compared to systems containing only one of these catalysts or systems containing two catalysts with a volume distribution between 50 vol% / 50 vol% and 90 vol% / 10 vol%, the activity and stability of the catalytic system are increased.

[0020] Another advantage of the hydrotreating method according to the invention is that it can treat both light feedstocks (gas oil) and heavy feedstocks (vacuum distillate) with equal efficiency. The hydrotreating method according to the invention is also particularly suitable for hydrotreating feedstocks containing high levels of nitrogen and aromatics, such as feedstocks produced by catalytic cracking, coking, or viscous cracking.

[0021] The method according to the invention produces a hydrotreated hydrocarbon fraction, i.e., a fraction simultaneously free of nitrogen-based compounds, sulfur-based compounds, and aromatic compounds. Preferably, according to the method of the invention, the hydrodesulfurization (HDS) conversion is greater than 95%, more preferably greater than 98%. Preferably, according to the method of the invention, the hydronitrogenation (HDN) conversion is greater than 90%, more preferably greater than 95%. Preferably, according to the method of the invention, the aromatic hydrogenation (HDA) conversion is greater than 70%, more preferably greater than 80%.

[0022] According to an alternative form, the volume V1 / V2 distributions are respectively between 60% / 40% and 85% / 15% of the first and second hydrogenation treatment reaction sections.

[0023] According to an alternative form, the volume V1 / V2 distributions are respectively between 70% / 30% and 80% / 20% of the first and second hydrogenation treatment reaction sections.

[0024] According to an alternative form, the second catalyst is characterized by: - The nickel content, measured in NiO form, is between 1% and 4% by weight relative to the total weight of the catalyst. - The molybdenum content, measured in the form of MoO3, is between 2% and 9% by weight relative to the total weight of the catalyst. - The tungsten content, measured in WO3 form, relative to the total weight of the catalyst, is between 18% and 40% by weight. - The phosphorus content, measured in the form of P₂O₅, is between 0.5% and 4% by weight relative to the total weight of the catalyst.

[0025] According to an alternative form, the second catalyst is characterized by: - The nickel content, measured in NiO form, is between 3% and 4% by weight relative to the total weight of the catalyst. - The molybdenum content, measured in the form of MoO3, is between 2% and 9% by weight relative to the total weight of the catalyst. - The tungsten content, measured in WO3 form, relative to the total weight of the catalyst, is between 29% and 40% by weight. - The phosphorus content, measured in the form of P₂O₅, is between 3% and 4% by weight relative to the total weight of the catalyst.

[0026] According to an alternative form, the second catalyst is further characterized by: - The molar ratio of WO3 / MoO3 is between 2 and 12.4 mol / mol. The molar ratio of NiO / (WO3+MoO3) is between 0.20 and 0.33 mol / mol. The molar ratio P₂O₅ / (WO₃ + MoO₃) is between 0.21 and 0.34 mol / mol.

[0027] According to an alternative form, the first catalyst has a molybdenum content between 5% and 40% by weight relative to the total weight of the catalyst, denoted as MoO3, and a nickel content between 1% and 10% by weight relative to the total weight of the catalyst, denoted as NiO.

[0028] According to an alternative form, the first catalyst further comprises a phosphorus content between 0.1% by weight and 20% by weight relative to the total weight of the catalyst, expressed as P₂O₅.

[0029] According to an alternative form, the first and / or second catalysts further comprise organic compounds containing oxygen and / or nitrogen and / or sulfur.

[0030] According to an alternative form, the organic compound is selected from compounds containing one or more chemical functional groups selected from carboxyl, alcohol, thiol, thioether, sulfide, sulfene, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, amide, oxime, urea, or amide functional groups, or also includes furan ring or sugar compounds, and preferably selected from γ-valerolactone, 2-acetylbeptylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, EDTA, maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovalerate, di(C1-C2) succinate. 4-alkyl) esters, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-butyrate, dihydroxyethylglycine, trimethylolpropionic acid, 2-furanaldehyde (also known as furfural), 5-hydroxymethylfurfural, 2-acetylglucan, 5-methyl-2-furanaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyrate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate. 2-Hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)-2,5-pyrrolidone, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutyric acid, butyl glycolate, ethyl 2-mercaptopropionate, ethyl 4-sideoxyvalerate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and dimethyl 3-sideoxyglutarate.

[0031] According to one alternative formulation, the content of organic compounds relative to the total weight of the catalyst is between 1% by weight and 30% by weight.

[0032] According to an alternative form, the first and / or second catalysts are at least partially sulfided.

[0033] According to an alternative form, the hydrotreatment method is a method for hydrodesulfurization (HDS) of gas oil fractions.

[0034] According to an alternative approach, the hydrotreating method is carried out as a pretreatment in a fluidized bed catalytic cracking process.

[0035] According to an alternative approach, the hydrotreating method is performed as a pretreatment within the hydrocracking process. Implementation

[0036] definition Subsequently, chemical element groups are assigned according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by DR. Lide, 81st edition, 2000-2001). For example, according to the CAS classification, Group VIII corresponds to the metals in rows 8, 9, and 10 of the new IUPAC classification.

[0037] It should be understood that the term "specific surface area" refers to the BET specific surface area (S BET, in m 2 / g) determined by nitrogen adsorption according to the standard ASTM D 3663-78, established by the Brunauer-Emmett-Teller method described in The Journal of the American Chemical Society, 1938, 60, 309.

[0038] It should be understood that the total pore volume of the catalyst or the support used to prepare the catalyst means the volume measured by mercury porosimetry at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dynes / cm and a contact angle of 140°, according to standard ASTM D4284-83. Following the recommendations in the publication "Techniques de l'ingénieur, traité analyze et caractérisation" [Techniques of the Engineer, Analysis and Characterization Treatise], pages 1050-1055, this wetting angle is taken as equal to 140°. For better accuracy, the total pore volume value corresponds to the total pore volume measured on the sample by mercury porosimetry minus the total pore volume measured on the same sample by mercury porosimetry at a pressure corresponding to 30 psi (approximately 0.2 MPa).

[0039] The content of metals from Group VIII and Group VIb was measured by X-ray fluorescence.

[0040] The contents of metals from Group VIb, metals from Group VIII, and phosphorus are expressed as oxides after correction for the loss on ignition of the catalyst sample at 550°C for two hours in a muffle furnace. This loss on ignition is due to moisture loss. It was determined according to ASTM D7348.

[0041] It should be understood that hydrotreatment includes, in particular, reactions involving hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and aromatic hydrogenation (HDA).

[0042] raw material The hydrocarbon feedstock to be processed by the hydrogenation method according to the present invention exhibits a distillation range between 150°C and 600°C, preferably between 180°C and 580°C.

[0043] Hydrocarbon feedstocks may have any chemical properties, that is, in addition to the aromatic content described below, they may have any distribution between different chemical families selected from paraffins, alkenes and cycloalkanes.

[0044] Feedstocks used in hydrotreating processes include, for example, gas oil, vacuum gas oil, atmospheric residue, vacuum residue, atmospheric distillate, vacuum distillate, heavy fuel oil, oil, wax and paraffin, waste oil, deasphalted residue or crude oil, feedstocks derived from thermal or catalytic conversion processes, lignocellulosic feedstocks, or more generally, feedstocks produced from biomass, such as vegetable oils, alone or in mixtures. The feedstocks used in the treatment (and especially those mentioned above) generally contain heteroatoms such as sulfur, oxygen and nitrogen, and for heavy feedstocks, they usually also contain metals.

[0045] The aromatic hydrocarbon content in the raw material is greater than or equal to 20% by weight, preferably between 25% by weight and 90% by weight, and more preferably between 30% by weight and 80% by weight. This aromatic hydrocarbon content is determined according to the method described in the publications Burdett RA, Taylor LW, and Jones LC, Journal of Molecular Spectroscopy, Rept. Conf., Inst. Petroleum, London, 1954, 30-41 (Pub. 1955).

[0046] The nitrogen content in the raw material is greater than or equal to 150 ppm, preferably between 200 and 10,000 ppm by weight, and even more preferably between 300 and 4,000 ppm by weight.

[0047] The sulfur content in the raw materials is generally between 0.01% by weight and 5% by weight, preferably between 0.2% by weight and 4% by weight, and even more preferably between 0.25% by weight and 3% by weight.

[0048] The hydrocarbon feedstock may contain metals, particularly nickel and vanadium, as required. The nickel and vanadium content of the combined hydrocarbon feedstock is preferably less than 50 ppm by weight, more preferably less than 25 ppm, and still more preferably less than 10 ppm.

[0049] The hydrocarbon feedstock may contain asphaltene as required. The asphaltene content of the hydrocarbon feedstock is generally less than 3000 ppm, preferably less than 1000 ppm, and even more preferably less than 200 ppm.

[0050] The hydrocarbon feedstock may contain resin as required. The resin content may be greater than 1% by weight, particularly greater than 5% by weight. This resin content is measured according to standard ASTM D 2007-11. The hydrocarbon feedstock may also contain very little resin (less than 1% by weight).

[0051] According to one embodiment, the hydrocarbon feedstock is advantageously selected from LCOs (light cycle oil or light gas oil produced by a catalytic cracking unit), atmospheric distillates (e.g., crude oil produced by direct distillation or gas oil produced by a conversion unit, such as fluidized bed catalytic cracking, coking or viscous cracking), or distillates from methods for desulfurization or hydroconversion of atmospheric residues in a fixed bed or fluidized bed, or mixtures of the above-mentioned feedstocks.

[0052] According to another embodiment, the hydrocarbon feedstock is advantageously selected from HCOs (heavy cycle oil (heavy gas oil produced by catalytic cracking unit)), vacuum distillates (e.g., gas oil produced by direct distillation of crude oil or by conversion units such as catalytic cracking, coking, or viscous cracking), feedstocks derived from units used for extracting aromatics, lubricating oil-based products, or produced by solvent dewaxing of lubricating oil-based products, distillates derived from methods for fixed-bed or fluidized-bed desulfurization or hydroconversion of atmospheric residues and / or vacuum residues and / or deasphalted oils, or the feedstock may be deasphalted oil or contain vegetable oils or otherwise derived from the conversion of feedstocks produced from biomass. The hydrocarbon feedstock processed by the hydrocracking method according to the invention may also be a mixture of the feedstocks mentioned above.

[0053] Implementation and operating conditions of the method The method according to the invention can be carried out in one, two or more reactors. It is typically carried out in a fixed bed.

[0054] When the method according to the invention is carried out in two reactors, stage a) may be carried out in a first reactor containing a first reaction section through which the feedstock passes, and then stage b) may be carried out in a second reactor containing a second reaction section, located downstream of the first reactor. If necessary, the effluent from stage a) exiting the first reactor may undergo a separation stage to separate light fractions containing, in particular, H₂S and NH₃ formed during the hydrotreating process in stage a) from heavy fractions containing partially hydrotreated hydrocarbons. The heavy fraction obtained after this separation stage is subsequently introduced into the second reactor to allow stage b) of the method according to the invention to be carried out. This separation stage may be carried out by distillation, quick distillation, or any other method known to those skilled in the art.

[0055] When the method is carried out in a single reactor, stage a) is carried out in a first region containing a first reaction section, and stage b) is carried out in a second region containing a second reaction section downstream of the first region.

[0056] The first hydrogenation reaction section containing the first catalyst occupies a volume V1, and the second hydrogenation reaction section containing the second catalyst occupies a volume V2. The distribution of these volumes V1 / V2 is between 50% / 50% and 90% / 10% of the first and second hydrogenation reaction sections, respectively, preferably between 60% / 40% and 85% / 15% and particularly preferably between 70% / 30% and 80% / 20% of the first and second hydrogenation reaction sections.

[0057] The volume distribution of the two catalysts, particularly the fact that the second reaction section containing the second catalyst occupies a smaller volume than the first reaction section containing the first catalyst, allows for the optimization of the HDS, HDN, and HDA reactions occurring in either the first or second reaction section. This is because an excessively large volume of the second catalyst makes it impossible to quantitatively decompose nitrogen-based compounds, thus inhibiting the HDA reaction. Conversely, an excessively small volume of the second catalyst makes it impossible to maximize the HDA reaction.

[0058] The operating conditions used in stage a) or b) of the hydrotreating method according to the present invention are generally as follows: temperature advantageously between 180°C and 450°C, and more preferably between 250°C and 440°C; pressure advantageously between 0.5 and 30 MPa, and more preferably between 1 and 18 MPa; and space velocity advantageously between 0.1 and 20 h⁻¹, and more preferably between 0.2 and 5 h⁻¹. Space velocity (HSV) is defined herein as the ratio of the hourly flow rate of the hydrocarbon feed volume to the catalyst volume. The hydrogen / feed ratio, expressed as the hydrogen volume measured under standard temperature and pressure conditions per volume of liquid feed, is advantageously between 50 l / l and 5000 l / l, and more preferably between 80 and 2000 l / l.

[0059] The operating conditions in stages a) and b) may be the same or different. Preferably, they are the same.

[0060] Composition of the catalyst used in this invention According to the present invention, the hydrotreating method uses a sequence of a first catalyst comprising a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel and molybdenum, and a second catalyst comprising a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel, molybdenum and tungsten, and phosphorus.

[0061] First catalyst The first catalyst comprises a support based on bauxite, silica, or silica-bauxite, and an active phase composed of nickel and molybdenum. It may also contain phosphorus, organic compounds, and, if necessary, boron and / or fluorine.

[0062] The hydrogenation function of the first catalyst (also known as the active phase) is provided by nickel and molybdenum.

[0063] Preferably, the total content of nickel and molybdenum relative to the total weight of the catalyst is advantageously greater than 6% by weight, expressed as oxides.

[0064] Preferably, the molybdenum content, measured in the form of MoO3, is between 5% and 40% by weight relative to the total weight of the catalyst, more preferably between 8% and 39% by weight, and even more preferably between 10% and 38% by weight.

[0065] Preferably, the nickel content, measured in the form of NiO, is between 1% and 10% by weight relative to the total weight of the catalyst, more preferably between 1.5% and 9% by weight, and even more preferably between 2% and 8% by weight.

[0066] Preferably, the molar ratio of nickel to molybdenum in the first catalyst is between 0.1 and 0.8, more preferably between 0.15 and 0.6, and even more preferably between 0.2 and 0.5.

[0067] The first catalyst may also contain phosphorus as a dopant. This dopant is an additive element that does not exhibit any catalytic properties on its own but increases the catalytic activity of the active phase.

[0068] The phosphorus content in the catalyst, measured in the form of P₂O₅, is between 0.1 wt% and 20 wt% relative to the total weight of the catalyst, preferably between 0.2 wt% and 15 wt%, and most preferably between 0.3 wt% and 11 wt% (expressed as P₂O₅).

[0069] The molar ratio of phosphorus to molybdenum in the first catalyst is greater than or equal to 0.05, preferably greater than or equal to 0.07, preferably between 0.08 and 1, preferably between 0.1 and 0.9, and most preferably between 0.15 and 0.8.

[0070] The first catalyst may also advantageously contain at least one dopant selected from boron, fluorine, and mixtures of boron and fluorine.

[0071] When the catalyst contains boron or fluorine or a mixture of boron and fluorine, the content of boron or fluorine or a mixture of the two (expressed as boron oxide and / or fluorine element) relative to the total weight of the catalyst is preferably between 0.1% by weight and 10% by weight, preferably between 0.2% by weight and 7% by weight, and most preferably between 0.2% by weight and 5% by weight.

[0072] The pore volume of the catalyst is generally between 0.1 cm³ / g and 1.5 cm³ / g, preferably between 0.15 cm³ / g and 1.1 cm³ / g. The total pore volume is measured by mercury porosimetry according to standard ASTM D4284 at a wetting angle of 140°, as described in the works of Rouquerol F., Rouquerol J., and Singh K., *Adsorption by Powders & Porous Solids: Principle, Methodology and Applications*, Academic Press, 1999, for example using a Micromeritics™ Autopore III™ model machine.

[0073] The first catalyst is characterized by a specific surface area between 5 and 400 m² / g, preferably between 10 and 350 m² / g, more preferably between 40 and 350 m² / g, and extremely preferably between 50 and 300 m² / g. This specific surface area is determined in this invention by the BET method according to standard ASTM D3663, which is described in the same work cited above.

[0074] The support of the first catalyst comprises bauxite or silica or silica-bauxite, and preferably is composed of thereto.

[0075] When the catalyst support is based on bauxite, the catalyst contains more than 50% by weight of bauxite relative to the total weight of the support, and generally it contains only bauxite or silica-bauxite as defined below.

[0076] Preferably, the support comprises bauxite and preferably the bauxite is extruded. Preferably, the support is composed of γ-bauxite.

[0077] The bauxite support advantageously displays a total pore volume between 0.1 and 1.5 cm³ g⁻¹, preferably between 0.4 and 1.1 cm³ g⁻¹. This total pore volume is measured, for example, by mercury porosimetry according to standard ASTM D4284 at a wetting angle of 140°, as described in the works of Rouquerol F., Rouquerol J., and Singh K., *Adsorption by Powders & Porous Solids: Principle, Methodology and Applications*, Academic Press, 1999, using a Micromeritics™ Autopore III™ model machine.

[0078] The specific surface area of ​​the bauxite support is advantageously between 5 and 400 m²·g⁻¹, more preferably between 10 and 350 m²·g⁻¹, and even more preferably between 40 and 350 m²·g⁻¹. In this invention, this specific surface area is determined by the BET method according to standard ASTM D3663, which is described in the same work cited above.

[0079] In another preferred embodiment, the catalyst support system contains at least 50% by weight of bauxite silica-bauxite relative to the total weight of the support. The silica content in the support is at most 50% by weight relative to the total weight of the support, typically less than or equal to 45% by weight, and preferably less than or equal to 40% by weight.

[0080] The sources of silicon are well known to those skilled in this technology. Examples include silicic acid, silica in powder or colloidal form (silicone sol), or tetraethyl orthosilicate Si(OEt)4.

[0081] When the catalyst support is based on silica, the catalyst contains more than 50% by weight of silica relative to the total weight of the support, and typically it contains only silica.

[0082] According to a particularly preferred alternative, the support is composed of bauxite, silica, or silica-bauxite.

[0083] Additionally, the support may advantageously contain zeolite. In this case, any zeolite source and any related preparation method known to those skilled in the art can be incorporated. Preferably, the zeolite is selected from the group FAU, BEA, ISV, IWR, IWW, MEI, UWY, and more preferably, the zeolite is selected from the group FAU and BEA, such as zeolite Y and / or β-zeolite, and particularly preferably, such as USY and / or β-zeolite. When zeolite is present, the zeolite content is from 0.1% by weight to 50% by weight relative to the total weight of the support.

[0084] The support is advantageously provided in the form of beads, extrusions, aggregates, or irregular and non-spherical aggregates, the specific shape of which can be produced by the crushing stage.

[0085] The first catalyst may further comprise organic compounds or groups of organic compounds known to function as additives. Compared to a catalyst without additives, the function of these additives is to increase catalytic activity. More particularly, the catalyst may further comprise one or more oxygen-containing organic compounds and / or one or more nitrogen-containing organic compounds and / or one or more sulfur-containing organic compounds. Preferably, the catalyst may further comprise one or more oxygen-containing organic compounds and / or one or more nitrogen-containing organic compounds. Preferably, the organic compound contains at least two carbon atoms and at least one oxygen and / or nitrogen atom, but no other heteroatoms.

[0086] Generally speaking, organic compounds are selected from compounds containing one or more chemical functional groups selected from carboxyl, alcohol, thiol, thioether, sulfonium, sulfene, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, acetylimine, oxime, urea or acetylamine functional groups, or also include furan ring or sugar compounds.

[0087] Oxygen-containing organic compounds may be selected from compounds containing one or more chemical functional groups selected from carboxyl, alcohol, ether, aldehyde, ketone, ester or carbonate functional groups, or also from compounds containing one or more furan rings or sugars. It should be understood here that an oxygen-containing organic compound means a compound that does not contain another heteroatom. For example, the oxygen-containing organic compound may be selected from one or more of the following groups: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (with a molecular weight between 200 and 1500 g / mol), propylene glycol, 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, triethylene glycol dimethyl ether, glycerol, acetophenone, 2,4-pentanedione, pentanone, acetic acid, oxalic acid, maleic acid, malic acid, malonic acid, gluconic acid, tartaric acid, citric acid, γ-ketovalerate, di(C1-C2) succinate. 4-alkyl) esters, and more particularly dimethyl succinate, methyl acetoacetate, ethyl acetoacetate, 2-methoxyethyl 3-butyrate, 2-methylpropenyl 3-butyrate, dibenzofuran, crown ether, phthalic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-valerolactone, 2-acetylbenolactone, propylene carbonate, 2-furanaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furanaldehyde or 5-HMF), 2-acetylburan, 5-methyl-2-furanaldehyde, methyl 2-furfurylate, furfuryl alcohol (also known as furanol), furfuryl acetate, ascorbic acid, butyl lactate, ethyl lactate, butyl butyrate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate methyl 3-methoxypropionate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,5-hexanediol, 3-ethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 5-methyl-2(3H)-furanone, butyl glycolate, ethyl 4-semi-oxypentanoate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, dimethyl 3-semi-oxypentanoate, dimethyl tartrate, diethyl tartrate, diisopropyl tartrate, di(tert-butyl) tartrate, dimethyl malate, diethyl malate, diisopropyl malate, and dibutyl malate.

[0088] Nitrogen-containing organic compounds may be selected from one or more compounds containing one or more chemical functional groups selected from amine or nitrile functional groups. It should be understood here that a nitrogen-containing organic compound means a compound that does not contain another heteroatom. For example, the nitrogen-containing organic compound may be selected from one or more of the following groups: ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, acetonitrile, octylamine, guanidine, and terazole.

[0089] Oxygen- and nitrogen-containing organic compounds may be selected from compounds containing one or more chemical functional groups selected from carboxyl, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, amide, amide, urea, or oxime functional groups. It should be understood here that oxygen- and nitrogen-containing organic compounds mean compounds that do not contain another heteroatom. For example, the oxygen- and nitrogen-containing organic compounds may be selected from one or more of the following groups: 1,2-cyclohexanediaminetetraacetic acid, monoethanolamine (MEA), 1-methyl-2-pyrrolidone, dimethylformamide, ethylenediaminetetraacetic acid (EDTA), alanine, glycine, nitrotriacetic acid (NTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), tetramethylurea, gluten Amino acids, dimethylglycine, dihydroxyethylglycine, trimethylolmethylglycine, 2-methoxyethyl cyanoacetate, 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)-2,5-pyrrolidone, 1-methyl-2-piperidone, 1-acetylglyl-2-azacycloheptaneone, 1-vinyl-2-azacycloheptaneone, and 4-aminobutyric acid.

[0090] The sulfur-containing organic compound may be selected from one or more compounds containing one or more chemical functional groups selected from thiols, thioethers, thiocyanates, or thiocyanates. For example, the sulfur-containing organic compound may be selected from one or more of the following groups: thioglycolic acid, 2,2'-thiodiethanol, 2-hydroxy-4-methylthiobutyric acid, thiocyanate derivatives of benzothiophene or thiocyanate derivatives of benzothiophene, ethyl 2-mercaptopropionate, methyl 3-(methylthio)propionate, and ethyl 3-(methylthio)propionate.

[0091] Preferably, the organic compound contains oxygen; preferably, it is selected from γ-valerolactone, 2-acetylated butyllactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovalerate, and di(C1-C2) succinate. 4-alkyl) esters, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-butyrate, dihydroxyethylglycine, trimethylolpropionic acid, 2-furanaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furanaldehyde or 5-HMF), 2-acetylglucan, 5-methyl-2-furanaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyrate lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, acetic acid 2-Butoxyethyl ester, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)-2,5-pyrrolidone, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutyric acid, butyl glycolate, ethyl 2-mercaptopropionate, ethyl 4-sideoxyvalerate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and dimethyl 3-sideoxyglutarate.

[0092] When oxygen- and / or nitrogen- and / or sulfur-containing organic compounds are present, the total content of them in the catalyst is generally between 1% by weight and 30% by weight, more preferably between 1.5% by weight and 25% by weight, and even more preferably between 2% by weight and 20% by weight, relative to the total weight of the catalyst.

[0093] During the preparation of the catalyst requiring a drying stage, the drying stage, which is continuous with the introduction of the organic compound, is carried out at a temperature below 200°C to allow for the retention of a preferred amount of at least 30%, a preferred amount of at least 50%, and a very preferred amount of at least 70% of the introduced organic compound, based on the residual carbon on the catalyst. This residual carbon is measured by elemental analysis according to ASTM D5373.

[0094] Second catalyst According to the present invention, the second catalyst comprises a support based on bauxite, silica, or silica-bauxite, and an active phase composed of nickel, molybdenum, and tungsten. The second catalyst according to the present invention also comprises phosphorus as a dopant. It may additionally contain organic compounds and / or, if necessary, boron and / or fluorine.

[0095] The hydrogenation function of this second catalyst (also known as the active phase) is composed of nickel, molybdenum, and tungsten.

[0096] The second catalyst is characterized by: - The nickel content, measured in NiO form, is between 1% and 4% by weight relative to the total weight of the catalyst. - The molybdenum content, measured in the form of MoO3, is between 2% and 9% by weight relative to the total weight of the catalyst. - The tungsten content, measured in WO3 form, relative to the total weight of the catalyst, is between 18% and 40% by weight. - The phosphorus content, measured in the form of P₂O₅, is between 0.5% and 4% by weight relative to the total weight of the catalyst.

[0097] Preferably, the second catalyst is characterized by: - The nickel content, measured in NiO form, relative to the total weight of the catalyst, is between 3 wt% and 4 wt%, preferably between 3.1 wt% and 3.9 wt%, and even more preferably between 3.2 wt% and 3.8 wt%. The molybdenum content, measured in the form of MoO3, relative to the total weight of the catalyst is between 2 wt% and 9 wt%, preferably between 2 wt% and 4 wt%, more preferably between 2.2 wt% and 3.8 wt%, and even more preferably between 2.5 wt% and 3.5 wt%. - The tungsten content, measured in WO3 form, relative to the total weight of the catalyst, is between 29 wt% and 40 wt%, preferably between 34 wt% and 40 wt%, more preferably between 35 wt% and 39.9 wt%, and even more preferably between 36 wt% and 39 wt%. - The phosphorus content, measured in the form of P2O5, is preferably between 3% and 4% by weight relative to the total weight of the catalyst, preferably between 3.1% and 3.9% by weight, and most preferably between 3.2% and 3.8% by weight.

[0098] Preferably, the WO3 / MoO3 molar ratio is between 2 and 12.4 mol / mol, more preferably between 5.3 and 12.4 mol / mol, more preferably between 5.7 and 11.1 mol / mol, and even more preferably between 6.4 and 9.7 mol / mol.

[0099] Preferably, the NiO / (WO3+MoO3) mole ratio is between 0.20 and 0.33 mol / mol, more preferably between 0.21 and 0.31 mol / mol, and even more preferably between 0.22 and 0.30 mol / mol.

[0100] Preferably, the P₂O₅ / (WO₃+MoO₃) mole ratio is between 0.21 and 0.34 mol / mol, more preferably between 0.22 and 0.33 mol / mol, and even more preferably between 0.23 and 0.32 mol / mol.

[0101] Catalysts based on an active phase composed of nickel, molybdenum, and tungsten in the presence of phosphorus (which is deposited on a support and exhibits a specific ratio between the different metals and / or the phosphorus described above) show excellent hydrotreating activity and stability due to synergistic effects, particularly in aromatic hydrogenation (HDA) but also in hydrodesulfurization (HDS) and / or hydronitrogenation (HDN).

[0102] Without being confined to any single theory, optimizing the content of various metals and phosphorus using specific ratios will yield an active phase that improves catalytic performance. This is because tungsten is known to be more active than molybdenum in aromatic hydrogenation; however, its sulfidation is more difficult. The proximity of molybdenum in the tungsten-containing active phase and the increase in the WO3 / MoO3 ratio allow for the improvement of the sulfidability and observed catalytic performance of tungsten to a specific WO3 / MoO3 ratio where the molybdenum content is too low to affect the sulfidability of the tungsten. Therefore, the optimization of the WO3 / MoO3 ratio, combined with the optimization of the NiO / (WO3+MoO3) and P2O5 / (WO3+MoO3) ratios, yields a catalyst with very high activity and stability in hydrotreatment, particularly in aromatic hydrogenation (HDA).

[0103] Therefore, a trimetallic catalyst with the specific ratio mentioned above is particularly desirable during the sequence upstream of the first bimetallic catalyst.

[0104] Furthermore, the catalyst exhibits a density of group VIb metals (Mo + W), expressed as the number of atoms of these metals per unit catalyst area, which is between 5 and 12 atoms of group VIb metals per nm² catalyst, preferably between 6 and 11, and more preferably between 7 and 10. The density of group VIb metals, expressed as the number of atoms of group VIb metals per unit catalyst area (the number of atoms of group VIb metals per nm² catalyst), is calculated (for example) by the following relationship: in: X Mo = weight % of molybdenum; XW = weight percentage of tungsten; NA = Avogadro's number, equal to 6.022 x 10^23; S = Specific surface area of ​​the catalyst (m² / g), measured according to standard ASTM D3663; MMo = Mole mass of molybdenum; MW = Mole mass of tungsten.

[0105] To illustrate with an example, if a catalyst contains 3% by weight of molybdenum oxide (MoO3) (i.e., 2.0% by weight of Mo) and 29.3% by weight of tungsten oxide and has a specific surface area of ​​122 m² / g, then the density d(Mo + W) is equal to: .

[0106] The second catalyst may also advantageously contain at least one dopant selected from boron, fluorine, and mixtures of boron and fluorine. When such a dopant is present, its content is as described with respect to the first catalyst.

[0107] The pore volume of the second catalyst is generally between 0.1 cm³ / g and 1.5 cm³ / g, preferably between 0.15 cm³ / g and 1.1 cm³ / g. The total pore volume is measured using a mercury porosimeter method according to standard ASTM D4284 at a wetting angle of 140°, as described in works such as Rouquerol F., Rouquerol J., and Singh K., Adsorption by Powders & Porous Solids: Principle, Methodology and Applications, Academic Press, 1999, for example, using a Micromeritics™ Autopore III™ model machine.

[0108] The second catalyst is characterized by a specific surface area between 5 and 400 m² / g, preferably between 10 and 350 m² / g, more preferably between 40 and 350 m² / g, and extremely preferably between 50 and 300 m² / g. This specific surface area is determined in this invention by the BET method according to standard ASTM D3663, which is described in the same work cited above.

[0109] The support for the second catalyst comprises bauxite, silica, or a silica-bauxite combination, and preferably is composed of such materials. This support system is as described with respect to the first catalyst. It may additionally comprise zeolite as described with respect to the first catalyst. It may be the same as or different from the support for the first catalyst.

[0110] The first catalyst according to the invention may further comprise an organic compound or a group of organic compounds, the properties and amounts of which are described in the section on the first catalyst. When two catalysts comprise one or more organic compounds, the latter may be the same or different.

[0111] According to a preferred embodiment, the hydrotreating method uses a sequence of a first hydrotreating reaction section containing a first catalyst based on nickel and molybdenum in the presence of phosphorus and a second hydrotreating reaction section containing a second catalyst based on nickel, molybdenum and tungsten in the presence of phosphorus. The first hydrotreating reaction section containing the first catalyst occupies a volume V1 and the second hydrotreating reaction section containing the second catalyst occupies a volume V2. The distribution of these volumes V1 / V2 is between 50% / 50% and 90% / 10% of the first and second hydrotreating reaction sections, respectively. The second catalyst is characterized in that: - The nickel content, measured in NiO form, relative to the total weight of the catalyst, is between 3 wt% and 4 wt%, preferably between 3.1 wt% and 3.9 wt%, and even more preferably between 3.2 wt% and 3.8 wt%. - The molybdenum content in the form of MoO3 relative to the total weight of the catalyst is between 2 wt% and 9 wt%, preferably between 2 wt% and 4 wt%, more preferably between 2.2 wt% and 3.8 wt%, and even more preferably between 2.5 wt% and 3.5 wt%. - The tungsten content, measured in WO3 form, relative to the total weight of the catalyst, is between 29 wt% and 40 wt%, preferably between 34 wt% and 40 wt%, more preferably between 35 wt% and 39.9 wt%, and even more preferably between 36 wt% and 39 wt%. - The phosphorus content in the catalyst, measured in the form of P₂O₅, is preferably between 3% and 4% by weight relative to the total weight of the catalyst, preferably between 3.1% and 3.9% by weight, and extremely preferably between 3.2% and 3.8% by weight; - The WO3 / MoO3 mol / mol ratio is between 2 and 12.4 mol / mol, preferably between 5.3 and 12.4 mol / mol, even more preferably between 5.7 and 11.1 mol / mol, and still more preferably between 6.4 and 9.7 mol / mol; The NiO / (WO3+MoO3) molar ratio is between 0.20 and 0.33 mol / mol, preferably between 0.21 and 0.31 mol / mol, and even more preferably between 0.22 and 0.30 mol / mol; The molar ratio of P₂O₅ / (WO₃+MoO₃) is between 0.21 and 0.34 mol / mol, preferably between 0.22 and 0.33 mol / mol, and even more preferably between 0.23 and 0.32 mol / mol.

[0112] According to this preferred embodiment, the first and / or second catalysts further comprise at least one oxygen- and / or nitrogen- and / or sulfur-containing organic compound.

[0113] According to this embodiment, the organic compound is preferably selected from γ-valerolactone, 2-acetylated butyllactone, triethylene glycol, diethylene glycol, ethylene glycol, EDTA, maleic acid, malonic acid, citric acid, acetic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovalerate, and di(C1-C2) succinate. 4-alkyl) esters, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-butyrate, dihydroxyethylglycine, trimethylolpropionic acid, 2-furanaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furanaldehyde or 5-HMF), 2-acetylglucan, 5-methyl-2-furanaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyrate lactate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, 2-ethoxyethyl acetate, acetic acid 2-Butoxyethyl ester, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)-2,5-pyrrolidone, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutyric acid, butyl glycolate, ethyl 2-mercaptopropionate, ethyl 4-sideoxyvalerate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and dimethyl 3-sideoxyglutarate.

[0114] Preparation method The first and second catalysts can be prepared according to any method known to those skilled in the art for preparing supported catalysts.

[0115] The first and second catalysts can be prepared according to a preparation method including the following stages: i) Nickel precursor, molybdenum precursor, tungsten precursor (in the presence of tungsten), and phosphorus (in the presence of phosphorus) are contacted with a bauxite- or silica- or silica-bauxite-based support to obtain catalyst precursors. ii) The catalyst precursor produced in stage i) is dried at a temperature below 200°C. iii) As needed, the catalyst precursor obtained in stage ii) is calcined at a temperature between 200°C and 550°C. iv) If necessary, sulfide the catalyst obtained in stage ii) or stage iii).

[0116] During the contact operation in stage i), the first and second catalysts can be prepared by impregnating the metal and phosphorus onto the selected support. This impregnation can be carried out, for example, in the term "dry impregnation" according to methods known to those skilled in the art, wherein only the desired amount of the element in the form of a soluble salt is introduced into the selected solvent (e.g., demineralized water) to fill the pores of the support as precisely as possible.

[0117] The precursors of the active phase can be introduced simultaneously or sequentially. Impregnation of each precursor can advantageously be performed at least twice. Therefore, different precursors can advantageously be impregnated sequentially with different impregnation and maturation times. One of these precursors can also be impregnated several times.

[0118] Preferably, a precursor of the active phase is introduced simultaneously.

[0119] The nickel precursors that can be used are advantageously selected from nickel oxide, nickel hydroxide, nickel hydroxycarbonate, nickel carbonate and nickel nitrate; for example, nickel hydroxycarbonate, nickel carbonate or nickel hydroxide are preferred.

[0120] The molybdenum precursors that can be used are well known to those skilled in the art. For example, in the molybdenum source, oxides and hydroxides, molybdic acid and its equivalent salts, especially ammonium salts such as ammonium molybdate or ammonium heptamolybdate, phosphomolybdic acid (H₃PMo₁₂O₄₀) and its equivalent salts, and, if necessary, silicomolybdic acid (H₄SiMo₁₂O₄₀) and its salts can be used. These molybdenum sources can also be, for example, Keggin, lacunary Keggin, substituted Keggin, Dawson, Anderson, or Strandberg type heteropolymers. Preferably, molybdenum trioxide and Strandberg, Keggin, lacunary Keggin, or substituted Keggin type heteropolymers are used.

[0121] The tungsten precursors that can be used are well known to those skilled in the art. For example, oxides and hydroxides, tungstic acid and its equivalent salts, especially ammonium salts such as ammonium tungstate or ammonium metatungstate, phosphotungstic acid and its equivalent salts, and, if necessary, silicottitic acid (H₄SiW₁₂O₄₀) and its salts can be used as tungsten sources. For example, these tungsten sources can also be coking, depleted coking, substituted coking, or Dawson-type heteropolymers. Oxides and ammonium salts, such as ammonium metatungstate, or coking, depleted coking, or substituted coking heteropolymers are preferred.

[0122] Phosphorus can be introduced completely or partially by impregnation. Preferably, it is introduced by impregnation, more preferably dry impregnation, using a solution containing nickel, molybdenum and tungsten precursors.

[0123] The phosphorus can be advantageously introduced alone or as a mixture with the active phase, and if the latter is introduced multiple times, this can be carried out during any of the impregnation stages of the hydrogenation function. If the latter is introduced separately from the hydrogenation function (as described later in the post-impregnation and pre-impregnation cases), the phosphorus can also be introduced wholly or partially during the impregnation of oxygen- and / or nitrogen- and / or sulfur-containing organic compounds. It can also be introduced at any stage of the synthesis of the self-supporting body. Thus, it can be introduced before, during, or after kneading the selected bauxite gel matrix, such as, for example, and preferably, aluminum hydroxide (boehmite) (which is a bauxite precursor).

[0124] The preferred phosphorus pre-system is orthophosphoric acid (H₃PO₄), but its salts and esters (such as ammonium phosphate) are also suitable. This phosphorus can also be introduced simultaneously with elements from Group VIb in the form of coking, vacant coking, substituted coking, or Stranberg heteropolymer anions.

[0125] Any impregnation solution described in this invention may contain any polar solvent known to those skilled in the art. The polar solvent used is advantageously selected from the group consisting of methanol, ethanol, water, phenol, and cyclohexanol (alone or in mixtures). Preferably, a polar protic solvent is used. A list of commonly used polar solvents and their dielectric constants can be found in "Solvents and Solvent Effects in Organic Chemistry," C. Reichardt, Wiley-VCH, 3rd edition, 2003, pp. 472-474. Preferably, the solvent used is water or ethanol, and particularly preferably water. In one possible embodiment, the impregnation solution may be solvent-free.

[0126] When the first or second catalyst further comprises a dopant selected from boron, fluorine, or a mixture of boron and fluorine, the introduction of such dopant can be carried out in the same manner as the introduction of phosphorus described above at various stages of preparation and in various ways.

[0127] The boron precursor may be boric acid, orthoboronic acid (H₃BO₃), ammonium diborate or ammonium pentaborate, boron oxide, or a borate ester. The boron may be introduced, for example, from a solution of boric acid in a water / alcohol mixture or a water / ethanolamine mixture. Preferably, if boron is introduced, the boron precursor is orthoboronic acid.

[0128] Fluorine precursors that can be used are well known to those skilled in the art. For example, fluoride anions can be introduced in the form of hydrofluoric acid or its salts. These salts are formed from alkali metals, ammonium, or organic compounds. In the latter case, the salt is advantageously formed in the reaction mixture by a reaction between an organic compound and hydrofluoric acid. Fluorine can be introduced, for example, by impregnation with an aqueous solution of hydrofluoric acid, ammonium fluoride, or ammonium difluoride.

[0129] When the first or second catalyst further comprises an oxygen- and / or nitrogen- and / or sulfur-containing organic compound, the latter is introduced prior to the drying stage ii). This organic compound is generally introduced by impregnation in the presence or absence of an active phase and phosphorus, and in the presence or absence of a solvent.

[0130] The introduction of the organic compound includes several embodiments, differing particularly in the timing of its introduction relative to the introduction of the metal. It can be carried out simultaneously with (co-impregnation) the metal, after (post-impregnation), or finally before (pre-impregnation), particularly during the preparation of the support, and preferably during molding or by impregnation onto a pre-formed support. The embodiments can be carried out individually or in combination in one or more stages.

[0131] Furthermore, the contact stage can combine at least two embodiments, such as co-impregnation and post-impregnation. According to an alternative embodiment, at least two contact embodiments are combined according to the contact operation of stage i), such as co-impregnation of an active phase and phosphorus with an organic compound, followed by drying at a temperature below 200°C, and then post-impregnation with an organic compound that may be the same as or different from the organic compound used for co-impregnation. The embodiments can be carried out individually or in combination in one or more stages.

[0132] The organic compound is advantageously introduced into the impregnation solution, which, depending on the preparation example, may be the same as or different from a solution containing an active phase and a phosphorus precursor in corresponding amounts: -Based on the components introduced into the impregnation solution, the molar ratio of the total amount of organic compounds and catalyst precursors from Group VIb elements (Mo for the first catalyst or (Mo and W) for the second catalyst) is between 0.01 and 5 mol / mol, preferably between 0.05 and 3 mol / mol, more preferably between 0.05 and 1.5 mol / mol, and extremely preferably between 0.1 and 1.2 mol / mol. -Based on the components introduced into the impregnation solution, the molar ratio of organic compound to nickel is between 0.02 and 17 mol / mol, preferably between 0.1 and 10 mol / mol, more preferably between 0.15 and 8 mol / mol, and most preferably between 0.6 and 5 mol / mol.

[0133] When several organic compounds are present, different mole ratios are applicable to each of the organic compounds present.

[0134] Advantageously, the impregnated support is allowed to mature after each impregnation stage. Maturation allows the impregnation solution to be uniformly dispersed within the support.

[0135] Any maturation stage described in this invention is advantageously carried out at atmospheric pressure, in a water-saturated atmosphere, and at a temperature between 17°C and 50°C, and preferably at ambient temperature. Generally, a maturation time between ten minutes and forty-eight hours, and preferably between thirty minutes and five hours, is sufficient. Longer time periods are not excluded, but do not necessarily provide any improvement.

[0136] According to stage ii) of the preparation method of the present invention, the catalyst precursor obtained in stage i) as needed is subjected to a drying stage at a temperature of less than 200°C, preferably between 50°C and 180°C, preferably between 70°C and 150°C, and most preferably between 75°C and 130°C.

[0137] The drying stage is advantageously carried out by any technique known to those skilled in the art. It is advantageously carried out at atmospheric pressure or under reduced pressure, and more preferably at atmospheric pressure. It is advantageously carried out in a transverse bed using hot air or any other hot gas. Preferably, when drying is carried out in a fixed bed, the gas system used is air or an inert gas, such as argon or nitrogen. Most preferably, the drying is carried out in a transverse bed in the presence of nitrogen and / or air. Preferably, the drying stage has a short duration between 5 minutes and 4 hours, more preferably between 30 minutes and 4 hours, and most preferably between 1 hour and 3 hours. When organic compounds are present, the drying is then carried out to preferentially retain at least 30% of the introduced organic compounds; preferably, based on the carbon remaining on the catalyst, this amount is greater than 50% and more preferably still greater than 70%. At the end of drying stage b), the dried catalyst is obtained.

[0138] Depending on the needs, the calcination stage (iii) can follow the drying stage (ii).

[0139] According to this alternative form, at the end of the drying stage ii), the calcination stage c) is carried out at a temperature between 200°C and 600°C, preferably between 250°C and 550°C, under an inert atmosphere (e.g., nitrogen) or an oxygen-containing atmosphere (e.g., air). The duration of this heat treatment is generally between 0.5 hours and 16 hours, preferably between 1 hour and 5 hours. After this treatment, the active phase is thus found to be in oxide form; therefore, the heteropolymer anion is converted into an oxide. Similarly, the catalyst no longer contains or contains very little organic compound when it has been introduced. However, the introduction of this organic compound during its preparation allows for increased dispersion of the active phase, thus resulting in a more active catalyst.

[0140] When organic compounds are present, the catalyst is preferably not calcined. It should be understood here that the term "calcination" refers to heat treatment at a temperature greater than or equal to 200°C in the presence of air or oxygen.

[0141] However, catalyst precursors can undergo a calcination stage before the introduction of organic compounds, especially after impregnation of the active phase and phosphorus.

[0142] The first or second catalyst may be a fresh catalyst, that is, a catalyst that has not previously been used as a catalyst in the catalytic unit and especially in the hydrotreating process.

[0143] The first or second catalyst according to the invention may also be a regenerated and / or recycled catalyst. It should be understood that a regenerated and / or recycled catalyst means a catalyst that has been used as a catalyst in a catalytic unit and, particularly in hydrotreatment and / or hydrocracking, has undergone at least one stage (e.g., by calcination (regeneration)) of partial or complete removal by coke. This regeneration can be carried out by any means known to those skilled in the art. The regeneration is generally carried out by calcination at a temperature between 350°C and 550°C, and generally between 400°C and 520°C, or between 420°C and 520°C, or between 450°C and 520°C; temperatures below 500°C are generally advantageous.

[0144] When the regenerated catalyst no longer contains sufficient active phase and / or phosphorus, or when it exhibits ratios other than the preferred ratios described above, the regenerated catalyst can be regenerated by introducing one or more precursors of the active phase and / or phosphorus into the regenerated catalyst. At least one organic compound may also be introduced simultaneously with or separately from the metal and phosphorus. When the catalyst contains this organic compound, the introduced organic compound may be the same as or different from the organic compound in the fresh catalyst. The operating conditions described above regarding maturation, drying, and optionally calcination and optionally sulfidation naturally apply to the context of this last embodiment.

[0145] When used in hydrotreating reactions, it is advantageous to convert the first and / or second catalysts into sulfidation catalysts to form their active system. This activation or sulfidation stage is carried out by methods well known to those skilled in the art, and advantageously in the presence of hydrogen and hydrogen sulfide under a sulfur-reducing atmosphere.

[0146] According to an alternative form, the first or second catalyst is advantageously subjected to a sulfidation stage after the drying stage ii) or optionally the calcination stage iii).

[0147] The catalyst is advantageously used for in-situ or ex-situ sulfidation. The sulfiding agent is H₂S gas, elemental sulfur, CS₂, thiols, sulfides and / or polysulfides, sulfur-containing compounds with a boiling point less than 400°C, or any other sulfur-containing compound used to activate the hydrocarbon feedstock for sulfidation of the catalyst. These sulfur-containing compounds are advantageously selected from alkyl disulfides, such as, for example, dimethyl disulfide (DMDS), alkyl sulfides, such as, for example, dimethyl sulfide, thiols, such as, for example, n-butyl mercaptan (or 1-butane mercaptan), and tri-nonyl polysulfide type polysulfide compounds. The catalyst can also be sulfided by sulfur contained in the feedstock to be sulfidated. Preferably, the catalyst is sulfided in-situ in the presence of the sulfiding agent and the hydrocarbon feedstock. Most preferably, the catalyst is sulfided in-situ in the presence of a hydrocarbon feedstock with added dimethyl disulfide.

[0148] Application of the method according to the present invention in the ULSD method for gas oil fractions According to a first embodiment, the hydrotreating method of the present invention is a method for hydrotreating, particularly for hydrodesulfurization (HDS) of gas oil fractions, carried out in the presence of the catalyst sequence. The hydrotreating method of the present invention aims to remove sulfur-based compounds present in the gas oil fraction to meet current environmental standards, i.e., the permissible sulfur content is up to 10 ppm. It also allows for a significant reduction in the aromatic and nitrogen content of the gas oil fraction to be hydrotreated.

[0149] The gas oil fraction to be hydrotreated according to the method of the invention contains 0.02% to 5.0% by weight of sulfur. It is advantageously produced by straight-run distillation (or straight-run gas oil), by a coking unit, by a viscous cracking unit, by a steam cracking unit, by a unit for hydrotreating and / or hydrocracking of heavy feedstocks, and / or by a catalytic cracking unit (fluid catalytic cracking). The gas oil fraction preferably exhibits at least 90% of compounds with boiling points between 250°C and 400°C at atmospheric pressure.

[0150] The method for hydrotreating the gas oil fraction according to the present invention is carried out under the following operating conditions: a temperature between 200°C and 400°C, preferably between 300°C and 380°C; a total pressure between 2 MPa and 10 MPa, and more preferably between 3 MPa and 8 MPa; a hydrogen volume ratio (expressed as the hydrogen volume measured under standard temperature and pressure conditions per volume of liquid feedstock) between 100 and 600 liters per liter, and more preferably between 200 and 400 liters per liter; and a space velocity (HSV) between 0.5 and 10 h⁻¹, preferably between 0.7 and 8 h⁻¹.

[0151] HSV corresponds to the reciprocal of the contact time, expressed in hours, and is defined by the flow rate ratio of the volume of liquid hydrocarbon feedstock corresponding to each volume of catalyst loaded in the reaction unit implementing the hydrotreating method according to the invention. The reaction unit implementing the method for hydrotreating this gas oil fraction according to the invention is preferably operated in a fixed-bed configuration.

[0152] Application of the method according to the invention in hydrocracking processes According to the second alternative form, the hydrotreating method according to the invention is advantageously carried out as a pretreatment in hydrocracking processes, and more particularly in "single-stage" or "two-stage" hydrocracking processes. This hydrocracking process allows petroleum fractions, particularly vacuum distillates (VD), to be converted into lighter and more upgradable products (gasoline, middle distillates). The hydrotreating method according to the invention aims to remove sulfur-based compounds, nitrogen-based compounds, or aromatic compounds present in the vacuum distillate.

[0153] It can process highly diverse raw materials. Generally, these materials contain at least 20% by volume and usually at least 80% by volume of compounds with a boiling point above 340°C at atmospheric pressure. The raw materials may be, for example, vacuum distillates and also derived from units used for extracting aromatics from self-lubricating oils or from solvent dewaxing of lubricating oils and / or deasphalted oils, or the raw materials may be deasphalted oils or paraffin produced by the Fischer-Tropsch process, or any mixture of the raw materials mentioned above. Generally, these raw materials have a T5 boiling point greater than 340°C at atmospheric pressure and more preferably still greater than 370°C at atmospheric pressure, meaning that 95% of the compounds present in the raw materials have a boiling point greater than 340°C and more preferably still greater than 370°C. The nitrogen content of the raw materials processed according to the method of the invention is generally greater than 200 ppm by weight, preferably between 500 and 10,000 ppm by weight. The sulfur content of the raw materials processed according to the method of the present invention is typically between 0.01% by weight and 5.0% by weight. The raw materials may contain metals (e.g., nickel and vanadium) as required. The asphaltene content is generally less than 3000 ppm by weight.

[0154] A "single-stage" hydrocracking method may first and generally include complete hydrotreating, which aims to completely convert the feedstock to HDN, HDS, and HDA before it is fed to the hydrocracking catalyst. This single-stage hydrocracking method is particularly advantageous when the hydrocracking catalyst(s) contains a support containing zeolite crystals. This complete hydrotreating of the feedstock results in only a limited conversion of the feedstock to a lighter fraction, which is insufficient and therefore must be completed on a more active hydrocracking catalyst. However, it should be noted that no effluent separation occurs between different catalyst beds: all effluent at the outlet of the hydrotreating catalyst bed is injected into the catalyst bed containing the hydrocracking catalyst(s) and then the resulting products are separated. This form of hydrocracking has alternative forms, which involve recycling the unconverted fraction to at least one of the hydrocracking catalyst beds for more complete conversion of the feedstock. Advantageously, the hydrotreating method according to the invention, including a specific sequence thereof, is carried out upstream of the hydrocracking catalyst in a single-stage hydrocracking method. In addition, it allows for limiting nitrogen content at the end of the pretreatment stage to protect the nitrogen-sensitive zeolite-based hydrocracking catalyst.

[0155] The two-stage hydrocracking method includes a first stage, the purpose of which is the same as in the single-stage method: to hydrotreat the feedstock, but also to achieve the latter's typical conversion rate of approximately 40% to 60%. The effluent from the first stage is subsequently separated, typically by distillation, most commonly referred to as intermediate separation, to separate the conversion products from the unconverted fraction. In the second stage of the two-stage hydrocracking method according to the invention, only the feedstock fraction unconverted during the first stage is processed. This separation makes the two-stage hydrocracking method according to the invention more selective for the middle distillate (kerosene + diesel) than the single-stage method according to the invention. This is because intermediate separation of the conversion products prevents them from being "over-cracked" on the hydrocracking catalyst in the second stage to produce naphtha and gas. Furthermore, it should be noted that the unconverted feedstock fraction processed in the second stage typically contains very low levels of NH3 and organic nitrogen-based compounds, generally less than 20 ppm by weight, and in practice even less than 10 ppm by weight.

[0156] The first stage is carried out in the presence of a specific catalyst sequence according to the invention and a hydrocracking catalyst to perform hydrocracking and generally about 40% to 60% conversion. The catalyst bed of the specific catalyst sequence according to the invention is advantageously located upstream of the hydrocracking catalyst. The second stage is generally carried out in the presence of a hydrocracking catalyst that is compositionally different from the catalyst used to carry out the first stage.

[0157] Hydrocracking methods are generally carried out at temperatures between 250°C and 480°C, advantageously between 320°C and 450°C, and more preferably between 330°C and 435°C, at pressures between 2 and 25 MPa, and more preferably between 3 and 20 MPa. The space-time velocity (HSV) of the feedstock relative to each catalyst volume is advantageously between 0.1 and 40 h⁻¹, more preferably between 0.2 and 12 h⁻¹, and extremely preferably between 0.4 and 6 h⁻¹. The hydrogen / feedstock ratio, expressed as hydrogen per cubic meter (m³) of hydrocarbon feedstock corresponding to standard cubic meters (Sm³) of hydrogen, is advantageously between 80 Sl / l and 5000 Sl / l, and more preferably between 100 and 2000 Sl / l. Methods for hydrocracking vacuum distillates cover a range of pressures and conversions, from mild hydrocracking to high-pressure hydrocracking. It should be understood that mild hydrocracking means hydrocracking that results in moderate conversion (generally less than 40%) and is operated at low pressure (preferably between 2 MPa and 6 MPa).

[0158] Hydrocracking catalysts are bifunctional, possessing both acid and hydrogenation / dehydrogenation functions. The acid function is provided by a porous support, typically with a surface area varying from 150 to 800 m²·g⁻¹ and exhibiting surface acidity, such as halogenated (especially chlorinated or fluorinated) bauxite, combinations of boron and alumina, amorphous or crystalline mesoporous aluminosilicates, and zeolites dispersed in an oxide binder. The hydrogenation / dehydrogenation function is provided by the presence of an active phase based on at least one metal from Group VIb of the periodic table and, if desired, at least one metal from Group VIII of the periodic table. The most common formulations are nickel-molybdenum (NiMo) and nickel-tungsten (NiW) types, while cobalt-molybdenum (CoMo) types are less common. After preparation, the hydrogenation / dehydrogenation function is usually present in oxide form. A common method for forming the hydrogenation / dehydrogenation phase of a hydrocracking catalyst involves depositing molecular precursors of at least one group VIb metal and, if desired, at least one group VIII metal onto an acid oxide support using a "dry impregnation" technique, followed by maturation, drying, and calcination stages, resulting in the formation of the oxidized form of the metal(s) used. Since the active and stable form used in hydrocracking processes is the sulfided form, these catalysts must undergo a sulfidation stage. This can be carried out in the unit of the relevant process (then refer to in-situ sulfidation) or before the catalyst is loaded into the unit (then refer to out-of-situ sulfidation).

[0159] Application of the method according to the present invention in FCC methods According to the third alternative, the hydrotreating method according to the invention is advantageously carried out as a pretreatment in a fluidized bed catalytic cracking (or FCC for fluidized bed catalytic cracking) process. This FCC process can be carried out under suitable cracking conditions in a manner known to those skilled in the art to produce hydrocarbon products with lower molecular weights. For example, an overview of catalytic cracking (its first industrial use dating back to 1936 (Huzite process) or 1942 for fluidized bed catalysts) can be found in Ullmann's Encyclopedia of Industrial Chemistry, Volume A 18, 1991, pages 61-64.

[0160] In FCC processes, a conventional catalyst comprising a matrix, additives as needed, and at least one zeolite is typically used. The amount of zeolite is variable but relative to the weight of the catalyst, it is typically 3% to 60% by weight, typically 6% to 50% by weight, and typically 10% to 45% by weight. The zeolite is typically dispersed in the matrix. Relative to the weight of the catalyst, the amount of additive is typically 0% to 30% by weight and typically 0% to 20% by weight. The amount of matrix is ​​indicated to make up to 100% by weight. The additive is generally selected from oxides of metals from Group IIa of the periodic table (such as, for example, magnesium oxide or calcium oxide), rare earth metal oxides, and titanates of metals from Group IIa. The matrix is ​​typically silica, bauxite, silica-bauxite, silica-magnesium oxide, clay, or a mixture of two or more of these products. The most commonly used zeolite is zeolite Y.

[0161] The cracking occurs in a generally vertical reactor, either in an upward (riser) or downward (drip) mode. The choice of catalyst and operating conditions depends on the desired products, which vary with the feedstock being processed, for example, as described in M. Marcilly's paper, pp. 990-991, published in revue de l'institut français du pétrole [Review of the French Institute of Petroleum], Nov.-Dec. 1975, pp. 969-1006. This operation is typically carried out at temperatures between 450°C and 600°C and in reactors for less than one minute, with residence times typically between 0.1 and 50 seconds.

[0162] In addition, pretreatment allows for limiting nitrogen content at the end of the pretreatment stage to protect the catalytic cracking catalyst based on nitrogen-sensitive zeolite.

[0163] Example The following examples demonstrate the significant gains in HDA and HDN activity achieved by using specific sequences according to the present invention.

[0164] Examples 1 to 3 describe the preparation of catalysts C1 to C3. The final composition of each catalyst in terms of metal and phosphorus, expressed in oxide form and relative to the weight of the catalyst, as well as the ratios of WO3 / MoO3, NiO / (WO3+MoO3) and P2O5 / (WO3+MoO3), are presented in Table 1 below.

[0165] Examples 4 through 7 describe the evaluation of different sequences of catalysts C1, C2, and C3 in aromatic hydrogenation (HDA) and hydrodenitrogenation (HDN) of gas oil.

[0166] Example 1: Preparation of NiMoP catalyst on bauxite C1 Nickel, molybdenum, and phosphorus were added to 100 g of bauxite support A1, which showed a loss on ignition of 4.9 wt%, a BET specific surface area of ​​230 m² / g, a pore volume of 0.78 ml / g, and an average pore diameter of 11.5 nm, measured by mercury porosimetry. This was defined as the median diameter by volumetric measurement using mercury porosimetry, and the support was provided in "extrusion" form. Support A1 showed a water absorption volume of 0.77 ml / g. The impregnation solution was prepared by dissolving 37.41 g of molybdenum oxide (Merck™, purity > 99.5 wt%), 11.96 g of nickel hydroxycarbonate (Merck™, purity 99.9 wt%), and 14.53 g of orthophosphoric acid solution (Merck™, 85 wt% in water) in 67.2 ml of distilled water at 90 °C. After dry impregnation, the extrudates were matured at ambient temperature for 24 h in a water-saturated atmosphere and then dried at 90 °C for 16 h. The dried impregnated support of catalyst C1 was subsequently dry impregnated with a solution containing a mixture of dimethyl succinate (DMSU) and acetic acid (75% purity). The molar ratios were: DMSU / Mo = 0.85 mol / mol, DMSU / acetic acid = 0.5 mol / mol. The catalyst underwent a second maturation stage in air at 20 °C for 3 h and then dried at 120 °C for 3 h in a transverse bed type oven. The resulting dried catalyst is denoted as C1. The final composition of catalyst C1 (expressed as oxides) is then as follows: MoO3 = 25.1 + / - 0.2 (wt%), NiO = 5.1 + / - 0.1 (wt%), and P2O5 = 6.0 + / - 0.1 (wt%).

[0167] Example 2: Preparation of NiMoWP catalyst on bauxite C2 Nickel, molybdenum, tungsten, and phosphorus were added to the same support A1 as presented in Example 1. The impregnation solution was prepared by dissolving molybdenum oxide (Merck™, purity > 99.5 wt%, 6.12 g), ammonium metatungstate hydrate (Merck™, ≥ 85.0 wt% WO3, 74.74 g), nickel nitrate hexahydrate (Merck™, purity 99.999 wt%, 26.07 g), and orthophosphoric acid solution (Merck™, 85 wt% in water, 10.24 g) in 68.3 ml of distilled water at 90 °C. After dry impregnating 100 g of support A1, the extrudate was matured at ambient temperature in a water-saturated atmosphere for 24 h and then dried at 90 °C for 16 h. The resulting dried catalyst is designated C2.

[0168] The final composition of catalyst C2 (expressed in oxide form) is as follows: MoO3 = 3.4 + / - 0.1 (wt%), WO3 = 36.6 + / - 0.2 (wt%), NiO = 3.7 + / - 0.1 (wt%) and P2O5 = 3.5 + / - 0.1 (wt%).

[0169] Example 3: Preparation of NiMoWP catalyst on bauxite C3 by post-addition of organic compound (ascorbic acid) 100 g of catalyst precursor C2, described above in Example 2 and provided in "extrusion" form, was impregnated with an aqueous solution containing 28.78 g of ascorbic acid (Merck™, 100% purity) in a volume equal to the pore volume of the catalyst precursor C2. The amounts involved were such that the ascorbic acid content was 0.5 mol / mol molybdenum and tungsten (corresponding to 1.9 mol / mol nickel). The extrusions were then matured at ambient temperature for 16 h in a water-saturated atmosphere. Catalyst precursor C3 was then dried at 120°C for 2 h to produce catalyst C3.

[0170] The final composition of catalyst C3 (expressed in oxide form) is as follows: MoO3 = 3.4 + / - 0.1 (wt%), WO3 = 36.6 + / - 0.2 (wt%), NiO = 3.7 + / - 0.1 (wt%) and P2O5 = 3.5 + / - 0.1 (wt%). catalyst % NiO by weight Weight % MoO 3 Weight % WO 3 Weight % P 2O 5 WO 3 / MoO 3 (mol / mol) NiO / (WO 3 + MoO 3) (mol / mol) P₂O₅ / (WO 3 + MoO 3) (mol / mol) C1 5.1 25.1 - 6.0 - 0.27 0.27 C2 3.7 3.4 36.6 3.5 6.7 0.27 0.27 C3 3.7 3.4 36.6 3.5 6.7 0.27 0.27 Table 1: Composition of catalysts C1, C2 and C3

[0171] Examples 4 to 7: Evaluation of the C1, C2, and C3 catalyst sequence in the aromatic hydrogenation (HDA) and hydrogenation denitrification (HDN) of gas oil Catalyst sequences derived from catalysts C1, C2, and C3 were tested in the aromatic hydrogenation (HDA) of gas oil.

[0172] The feedstock is a mixture of 30% by volume gas oil produced by atmospheric distillation (also known as straight-run distillation) and 70% by volume light gas oil (also known as light recycled oil LCO) produced by a catalytic cracking unit. The characteristics of the test feedstock used are as follows: density at 15°C = 0.8994 g / cm³ (NF EN ISO 12185), refractive index at 20°C = 1.5143 (ASTM D1218-12), sulfur content = 0.38 wt%, nitrogen content = 0.05 wt%.

[0173] • Simulated distillation (ASTM D2887): - IP: 133℃; - 10%: 223℃; - 50%: 285℃; - 90%: 357℃; - FP: 419℃.

[0174] The tests were conducted in an isothermal pilot reactor with a transverse fixed bed, with the fluid circulating upwards from the top. The reactor contained two catalytic zones to allow evaluation of different sequences of the catalyst C1, C2, and C3. The feedstock first traversed a first zone containing a first catalyst and then a second zone containing a second catalyst.

[0175] According to Example 4 (in accordance with the present invention), the first region is filled with catalyst C1 (75% by volume) and then the second region is filled with catalyst C2 (25% by volume).

[0176] According to Example 5 (in accordance with the present invention), the first region is filled with catalyst C1 (75% by volume) and then the second region is filled with catalyst C3 (25% by volume).

[0177] According to Example 6 (not according to the invention), a first region is filled with catalyst C1 (40% by volume) and then a second region is filled with catalyst C2 (60% by volume).

[0178] According to Example 7 (not according to the invention), a first region is filled with catalyst C1 (95% by volume) and then a second region is filled with catalyst C2 (5% by volume).

[0179] The catalyst was pre-sulfurized in situ in a reactor at 350°C under pressure using atmospheric (straight-run) distilled gas oil feedstock (density = 0.8491 g / cm³ at 15°C (NF EN ISO 12185) and initial sulfur content = 0.42 wt%), with 2 wt% dimethyl disulfide added to it.

[0180] Catalytic testing was conducted under the following operating conditions: a total pressure of 8 MPa, a total volume of 4 cm³ for the two catalytic zones, a temperature of 330 °C, a hydrogen flow rate of 3.0 L / h, and a feed flow rate of 4.5 cm³ / h.

[0181] Analyze the characteristics of the effluent: density at 15°C (NF EN ISO 12185), refractive index at 20°C (ASTM D1218-12), simulated distillation (ASTM D2887), sulfur content, and nitrogen content. The residual aromatic carbon content is calculated using the ndM method (ASTM D3238). The degree of aromatic hydrocarbon hydrogenation is calculated as the ratio of the aromatic carbon content in the feedstock (subtracting the aromatic carbon content in the effluent) to the aromatic carbon content in the test feedstock. The degree of hydrodenitrogenation is calculated as the ratio of the nitrogen content in the feedstock (subtracting the nitrogen content in the effluent) to the nitrogen content in the test feedstock.

[0182] The catalytic performance of the tested catalyst sequences is given in Table 2. They are expressed as relative volumetric activity (RVA) relative to the sequence of 95 vol% catalyst C1 (first zone of reactor) + 5 vol% catalyst C2 (second zone of reactor) selected as reference (Example 7), with an assumption of about 1.7 for HDA reaction and about 1 for HDN reaction.

[0183] Table 2 clearly shows the gain in catalytic effect contributed by the specific sequence according to the present invention. This is because the catalyst sequence according to the present invention can significantly increase the volumetric activity in the hydrodearomatization (HDA) and hydrodenitrogenation (HDN) reactions of gas oil. Example Catalyst loaded into the reactor (Region 1 / Region 2) RVA HDA RVA HDN 4 (According to the present invention) 75 vol% catalyst C1 + 25 vol% catalyst C2 110 104 5 (According to the present invention) 75 vol% catalyst C1 + 25 vol% catalyst C3 125 108 6 (Not based on this invention) 40 vol% catalyst C1 + 60 vol% catalyst C2 96 91 7 (Not based on this invention) 95 vol% catalyst C1 + 5 vol% catalyst C2 100 100 Table 2: Relative activities of HDA and HDN for specific sequences according to the present invention (Examples 4 and 5) and those not according to the present invention (Examples 6 and 7).

Claims

1. A hydrotreating method for obtaining a hydrotreated effluent from a hydrocarbon feedstock having a distillation range between 150°C and 600°C at a temperature between 180°C and 450°C, a pressure between 0.5 and 30 MPa, a space velocity between 0.1 and 20 h⁻¹, and a hydrogen / feed ratio between 50 l / l and 5000 l / l, wherein the hydrogen / feed ratio is expressed as the volume of hydrogen measured under standard temperature and pressure conditions per volume of liquid feedstock, the method comprising the following stages: a) A first hydrotreating stage is carried out in a first hydrotreating reaction section using at least one catalyst bed comprising at least one first hydrotreating catalyst. The hydrotreating reaction section is fed by at least the hydrocarbon feedstock and a hydrogen-containing gas stream. The first catalyst comprises a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel and molybdenum. The first catalyst has a molybdenum content (MoO3) between 5% and 40% by weight relative to the total weight of the catalyst, and a nickel content (NiO) between 1% and 10% by weight relative to the total weight of the catalyst. The first catalyst also contains a phosphorus content (P2O5) between 0.1% and 20% by weight relative to the total weight of the catalyst. (b) The second hydrotreating stage is carried out in the second hydrotreating reaction section using at least one catalyst bed comprising at least one second hydrotreating catalyst. This hydrotreating reaction section is fed with at least a portion of the effluent obtained in stage a). The second catalyst comprises a support based on bauxite or silica or silica-bauxite and an active phase composed of nickel, molybdenum, tungsten, and phosphorus. The second catalyst is characterized by: a nickel content, measured as NiO, between 3% and 4% by weight relative to the total weight of the catalyst; a molybdenum content, measured as MoO3, between 2% and 9% by weight relative to the total weight of the catalyst; a tungsten content, measured as WO3, between 29% and 40% by weight relative to the total weight of the catalyst; a phosphorus content, measured as P2O5, between 3% and 4% by weight relative to the total weight of the catalyst; a molar ratio of WO3 / MoO3 between 2 and 12.4 mol / mol; and a molar ratio of NiO / (WO3 + ... The concentration of MoO3 is between 0.20 and 0.33 mol / mol, the molar ratio of P2O5 / (WO3 + MoO3) is between 0.21 and 0.34 mol / mol, the first hydrogenation reaction section containing the first catalyst occupies a volume V1 and the second hydrogenation reaction section containing the second catalyst occupies a volume V2, and the volume V1 / V2 distribution is between 50% / 50% and 90% / 10% of the first and second hydrogenation reaction sections, respectively.

2. The hydrogenation treatment method of claim 1, wherein the distribution of the volumes V1 / V2 is between 60% / 40% and 85% / 15% of the first and second hydrogenation treatment reaction sections, respectively.

3. The hydrogenation treatment method of claim 2, wherein the distribution of the volumes V1 / V2 is between 70% / 30% and 80% / 20% of the first and second hydrogenation treatment reaction sections, respectively.

4. The hydrotreating method of any one of claims 1 to 3, wherein the first and / or the second catalyst further comprises an oxygen- and / or nitrogen- and / or sulfur-containing organic compound.

5. The hydrogenation treatment method of claim 4, wherein the organic compound is selected from compounds containing one or more chemical functional groups selected from carboxyl, alcohol, thiol, thioether, sulfonium, sulfene, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, acetylimine, oxime, urea or acetylamine functional groups, or also contains furan ring or sugar.

6. The hydrogenation treatment method as claimed in claim 5, wherein the organic compound is selected from γ-valerolactone, 2-acetylborolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovalerate, di(C1-C4 alkyl) succinate, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidone, propylene carbonate, 2-methoxyethyl 3-butyrate, dihydroxyethylglycine, trimethylolmethylglycine (tricine), 2-furanaldehyde (also known as furfural), 5-hydroxymethylfurfural, 2-acetylburan, 5-methyl-2-furanaldehyde, Ascorbic acid, butyl lactate, ethyl lactate, butyl butyrate, ethyl 3-hydroxybutyrate, ethyl 3-ethoxypropionate, ethyl 2-ethoxyacetate, ethyl 2-butoxyacetate, ethyl 2-hydroxyacrylate, 1-vinyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-(2-hydroxyethyl)-2,5-pyrrolidone, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutyric acid, butyl glycolate, ethyl 2-mercaptopropionate, ethyl 4-semi-oxyvalerate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and dimethyl 3-semi-oxyvalerate.

7. The hydrogenation treatment method of claim 4, wherein the content of the organic compound relative to the total weight of the catalyst is between 1% by weight and 30% by weight.

8. The hydrotreating method of any one of claims 1 to 3, wherein the first and / or the second catalyst is at least partially based on sulfur.

9. The hydrotreatment method described in any of claims 1 to 3 is a method for hydrotreating gas oil fractions.

10. The hydrotreating method described in any of claims 1 to 3 is carried out as a pretreatment in a fluidized bed catalytic cracking method.

11. The hydrotreating method described in any of claims 1 to 3 is performed as a pretreatment in a hydrocracking method.

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