Method for preparing a boron-doped alumina with boron addition during alumina synthesis

Abstract

The present invention relates to the preparation of a boron-containing alumina shaped from a boehmite gel in which at least one boron source is added in the step or steps of precipitating at least one aluminum salt to form a boehmite gel. The boron-containing alumina according to the invention, owing to its advantageous properties, can be used as a support for catalysts in all refining processes and also as an adsorbent, in particular for catalytic processes treating hydrocarbon cuts such as the hydrotreating of vacuum distillates.

Description

[0001] PROCESS FOR PREPARING A BORON-DOPED ALUMINUM WITH THE ADDITION OF BORUM TO THE ALUMINUM SYNTHESIS

[0002] technical field

[0003] The present invention relates to the preparation of a mesoporous alumina containing boron formed from a boehmite gel in which at least one boron precursor is added in the precipitation step of at least one aluminum salt to form a boehmite gel.

[0004] Boron-containing alumina according to the invention, due to its interesting properties, can be used as a catalyst support in all refining processes as well as an adsorbent, in particular for catalytic processes dealing with hydrocarbon cuts such as vacuum hydrotreating of distillates.

[0005] Previous art

[0006] US patent application 2006249429A1 describes the preparation of a hydrotreating catalyst and catalyst support based on alumina, optionally containing 0.5 to 10 wt% phosphorus and also containing at least one element selected from Si, Ti, Zr, Mg, Ca, and B, with a percentage of these elements from 1 to 10 wt% relative to the support. The element is preferably Si, Ti, or B alone or in combination, and most preferably Si. The Ti-B and Si-B combinations are described. Boron is introduced onto the alumina as oxide, hydroxide, nitrate, or sulfate, either solid or in solution, at any stage of its preparation. The support may be impregnated with a solution containing one of these elements after its calcination. Preferably, said element is added at any stage prior to the calcination of the alumina. Hydrotreating catalysts have a pore diameter determined by the BET method between 6 and 9 nm.

[0007] Example 7 shows the preparation of a catalyst containing Si and boron, where boron is introduced as boric acid mixed with an acidic aluminum source during the co-precipitation step with basic Si and Al sources. The pH of the resulting suspension is 7. The percentage of boron considered in its oxide form (B₂O₃) is 2.1% relative to the support. The average pore diameter is 6.8 nm.

[0008] Patent application JP07299367 describes the preparation of an alumina-based hydrotreating catalyst containing boron (B₂O₃) with a B₂O₃ content ranging from 3 to 15% by mass relative to the support. The boron is introduced as boric acid after the synthesis and filtration of alumina hydrate. The catalyst exhibits a mean mesopore diameter, measured by mercury porosimetry, of between 9 and 12 nm, with 60% of the pore volume within the mean diameter ±1 nm.

[0009] US patent 4724226 describes methods for preparing catalyst supports and catalysts containing alumina and boron oxide. Preferably, the support contains between 0.1 and 5% boron oxide. The boron source can be introduced into the catalyst by mixing a boric acid solution with alumina powder until an extrusion paste is obtained, or the boric acid solution can be impregnated onto the shaped alumina. The boron source can also be added during the precipitation of the alumina.

[0010] In Example 1, the catalyst support is obtained by one-step coprecipitation of a mixture of aluminum sulfate, sodium aluminate, and sodium metaborate (Na₂B₂O₄) at a temperature of 60–70°C and a pH of 7.4. The resulting support contains 0.5% boron oxide and has a macroporous volume of 0.121 ml / g with a mean diameter of 240 nm and a microporous volume of 0.723 ml / g with a mean diameter of 13.9 nm. The BET surface area of ​​the coprecipitated support is 208 m². 2 / g. According to the authors, the presence of macroporosity allows large molecules to penetrate inside the catalyst.

[0011] The applicant highlighted that the addition of a boron source in one or more precipitation steps of a bohemite gel, the said precipitation step(s) being implemented under specific conditions, made it possible to obtain a boron-doped alumina exhibiting textural properties suitable for its use as a catalyst support in hydrotreating reactions of hydrocarbon feedstocks such as vacuum hydrotreating of distillates.

[0012] Summary and significance of the invention

[0013] In particular, the present invention relates to a process for preparing boron-containing alumina, said process comprising at least the following steps: a) at least one or more steps of precipitating a boehmite gel, in an aqueous reaction medium, by the simultaneous addition of at least one basic precursor selected from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulfate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of the basic or acid precursors comprises aluminum, the relative flow rate of the acidic and basic precursors being chosen so as to obtain a pH of the reaction medium between 8.9 and 10,0 and the flow rate of the aluminum-containing acid and basic precursor(s) is adjusted to obtain a rate of advancement of said first step between 15 and 100% and preferably between 17 and 100%, the rate of advancement being defined as the proportion of boehmite gel formed in Al2O3 equivalent during said first precipitation step relative to the total quantity of boehmite gel formed in Al2O3 equivalent at the end of the precipitation step(s) implemented, said precipitation step operating at a temperature between 20 and 80°C, and for a duration between 2 minutes and 30 minutes, b) optionally one or more heat treatment step(s) of the suspension obtained at the end of step a) at a temperature between 70 and 100°C for a duration between 30 minutes and 5 hours,(c) a filtration step of the suspension obtained at the end of heat treatment step (a) or optionally at the end of step (b), followed by at least one washing step of the resulting boehmite gel; (d) a drying step of the boehmite gel obtained at the end of step (c) to obtain a powder; (e) a shaping step of the powder obtained at the end of step (d) to obtain the raw material; (f) a drying step of the raw material obtained in shaping step (e) carried out at a temperature between 20 and 200°C and for a duration of between 1 hour and 3 weeks to obtain a dried raw material; (g) a heat treatment step of the dried raw material obtained at the end of step (f) at a temperature between 500 and 1000°C, and for a duration of between 1 and 12 hours, with or without an airflow containing up to 60% by volume. water,said process being characterized in that at least one boron source is added in at least one or more of said step(s) a) of precipitation and / or optionally in said step(s) b) of heat treatment in the case where one or more step b) is / are implemented.

[0014] The process according to the present invention allows the production of alumina containing boron having textural properties suitable for use as a catalyst support. Another object of the present invention is alumina containing boron prepared by the process according to the invention having textural properties suitable for use as a catalyst support.

[0015] The process of the present invention may also advantageously include at least one step of depositing at least one metal from group VIII, and / or at least one metal from group VI B, optionally at least one dopant selected from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive on said alumina containing boron prepared according to the invention.

[0016] Another object of the present invention is a hydrotreating process for feedstocks selected from hydrocarbon cuts having a distillation range between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks selected from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in mixtures, and feedstocks from the reprocessing of biomass and / or plastics and / or tires and / or household waste, alone or in mixtures, said process employing a catalyst comprising at least one metal from group VIII, at least one metal from group VI B, optionally at least one dopant selected from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive and a support comprising and preferably consisting of said alumina comprising boron prepared according to the preparation process according to the invention.

[0017] One advantage of the invention is that it provides a new, inexpensive method for preparing boron-containing alumina compared to conventional prior art alumina preparation methods, such as sol-gel processes. In particular, the method according to the invention does not involve autoclaving, and each unit step of the process is economically attractive and has already been proven on an industrial scale.

[0018] Finally, another advantage of the preparation process according to the invention is that it allows the production of catalyst supports and associated catalysts with unsurpassed performance compared to catalysts containing or not containing boron described in the prior art.In particular, the hydrotreating activity of feeds selected from hydrocarbon cuts having a distillation range between 250°C and 600°C and renewable feeds selected from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in mixtures, and feeds from the reprocessing of biomass and / or plastics and / or tires and / or household waste, alone or in mixtures, and in particular the hydrotreating of vacuum distillate cuts of a catalyst comprising the alumina support including boron prepared according to the invention is significantly superior to that of catalysts containing or not containing boron, prepared according to any prior art method known to the person skilled in the art.

[0019] In the following text, chemical element groups are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IIIPAC classification, and group VI B to the metals in column 6.

[0020] In the following text, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included within the described range of values. If this were not the case and the limit values ​​were not included within the described range, this clarification will be provided by the present invention.

[0021] In this description, the expression "greater than..." is understood as strictly greater, and symbolized by the sign ">", and the expression "less than" as strictly less, and symbolized by the sign "<".

[0022] Definitions and measurement methods.

[0023] The alumina according to the present invention has a specific pore distribution, where the macroporous and mesoporous volumes are measured by mercury intrusion and the microporous volume is measured by nitrogen adsorption.

[0024] By "macropores" we mean pores with an opening greater than 50 nm.

[0025] By "mesopores" we mean pores whose opening is between 2 nm and 50 nm, inclusive.

[0026] By "micropores" we mean pores whose opening is strictly less than 2 nm.

[0027] In the following description of the invention, the pore distribution measured by mercury porosimetry is determined according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140°. The wetting angle was taken to be 140° following the recommendations of the book "Techniques de l'ingénieur, traité analyse et caractérisation, P 1050-5, written by Jean Charpin and Bernard Rasneur".

[0028] We set at 0.2 MPa the value from which mercury fills all intergranular voids, and we consider that beyond this point mercury penetrates the pores of alumina.

[0029] To obtain better accuracy, the value of the total pore volume corresponds to the value of the total pore volume measured by mercury porosimetry measured on the sample less the value of the total pore volume measured by mercury porosimetry measured on the same sample for a pressure corresponding to 30 psi (approximately 0.2 MPa).

[0030] The macroporous volume is defined as the cumulative volume of mercury introduced at a pressure between 0.2 MPa and 30 MPa, corresponding to the volume contained in pores with an apparent diameter greater than 50 nm.

[0031] The mesoporous volume is defined as the cumulative volume of mercury introduced at a pressure between 30 MPa and 400 MPa, corresponding to the volume contained in pores with an apparent diameter between 3 and 50 nm.

[0032] The volume of the micropores is measured by nitrogen porosimetry. Quantitative analysis of microporosity is carried out using the "t" method (Lippens-De Boer method, 1965), which corresponds to a transform of the initial adsorption isotherm as described in the book "Adsorption by powders and porous solids. Principles, methodology and applications" by F. Rouquérol, J. Rouquérol and K. Sing, Academic Press, 1999.

[0033] The average diameter of mesopores (Dp in nm) is also defined as a diameter such that all pores smaller than this diameter constitute 50% of the mesoporous volume, measured by mercury porosimetry.

[0034] In the following description of the invention, the term "specific surface area" refers to the specific surface area BET determined by nitrogen adsorption in accordance with ASTM D 3663-78, established from the Brunauer-Emmett-Teller method described in "The Journal of the American Society," 60, 309, (1938). X-ray diffraction on the boehmite gels was performed using the conventional powder diffraction method with a diffractometer.

[0035] The Scherrer formula is a formula used in X-ray diffraction on polycrystalline powders or samples that relates the full width at half maximum (FWHM) of the diffraction peaks to the crystallite size. It is described in detail in the reference: Appl. Cryst. (1978). 11, 102-113. Scherrer after sixty years: A survey and some new results in the determination of crystallite size, J.I. Langford and A.J.C. Wilson.

[0036] Description of the invention

[0037] Step a) of precipitation

[0038] According to the invention, said preparation process comprises at least one or more steps a) of precipitating a boehmite gel in an aqueous reaction medium by the simultaneous addition of at least one basic precursor selected from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide, and potassium hydroxide, and at least one acidic precursor selected from aluminum sulfate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rates of the acidic and basic precursors are chosen to obtain a pH of the reaction medium between 8.9 and 10.0, and the flow rate of the aluminum-containing acidic and basic precursor(s) is adjusted to obtain a degree of completion of the first step between 15 and 100%, and preferably between 17 and 100%,the rate of advancement being defined as the proportion of boehmite gel formed in Al2O3 equivalent during said step a) of precipitation or each of the precipitation steps implemented, relative to the total quantity of boehmite gel in Al2O3 equivalent formed at the end of the precipitation step(s) and more generally at the end of the boehmite gel preparation steps, said step a) operating at a temperature between 20 and 80°C, and for a duration between 2 and 40 minutes.

[0039] Generally, the "progress rate" of the nth precipitation step refers to the percentage of boehmite gel formed in Al₂O₃ equivalent in said nth step, relative to the total quantity of boehmite gel formed at the end of all the precipitation steps and, more generally, at the end of the boehmite gel preparation steps. This nth precipitation step typically yields a boehmite gel suspension with an Al₂O₃ concentration between 20 and 100 g / L, preferably between 20 and 80 g / L, and more preferably between 20 and 60 g / L.

[0040] The simultaneous mixing in the aqueous reaction medium of at least one basic precursor and at least one acidic precursor requires either that at least the basic precursor or the acidic precursor includes aluminium, or that both the basic and acidic precursors include aluminium.

[0041] Basic precursors containing aluminum include sodium aluminate and potassium aluminate. Sodium aluminate is the preferred basic precursor.

[0042] The acidic precursors containing aluminum are aluminum sulfate, aluminum chloride, and aluminum nitrate. The preferred acidic precursor is aluminum sulfate. Preferably, the basic and acidic precursor(s) are added in said first precipitation step a) in aqueous solutions.

[0043] Preferably, the aqueous reaction medium is water.

[0044] Preferably, said step a) is carried out under agitation.

[0045] Preferably, said step a) is carried out in the absence of a silica source.

[0046] According to the invention, at least one source of boron is added in at least one or more of said precipitation step(s) a).

[0047] The said source of boron is advantageously chosen from boric acid (H3BO3), sodium tetraborate decahydrate (Na2B4O?*10H2O), sodium metaborate (NaBCh), ammonium pentaborate tetrahydrate ((NH^BsOs FW), ammonium tetraborate tetrahydrate (H8B4N2O7 H2O) or any other boron salt, alone or in mixture and preferably from boric acid (H3BO3) and ammonium tetraborate tetrahydrate (H8B4N2O7 H2O), alone or in mixture.

[0048] Preferably, the reaction medium for step a) is water.

[0049] According to the invention, at least said basic aluminum precursor and at least said acidic aluminum precursor are added simultaneously to the reaction medium of step a) to maintain the pH constant in said step a).

[0050] Preferably, the boron source is added to the aqueous reaction medium in aqueous solution, preferably in the water foot, before the simultaneous addition of the basic aluminum precursor and the acidic aluminum precursor, without having been previously mixed with either of said acidic or basic aluminum precursors.

[0051] At least part and preferably all of the desired quantity of boron source is added during the said step(s) a) of precipitation.

[0052] Preferably the boron source is introduced in full in the said step(s) a).

[0053] In the case where said process according to the invention comprises several precipitation steps a) the boron source can advantageously be added, in part, in each of the precipitation steps implemented and preferably in full in the first precipitation step.

[0054] The quantity of boron source added in said step(s) a) is adjusted so that the final alumina obtained comprises a boron content between 0.1 and 10% by weight, preferably between 0.5 and 9% and even more preferably between 0.8 and 6%, relative to the total weight of said alumina in Al2O3 equivalent.

[0055] The acidic and basic precursors, whether they contain aluminum or not, are mixed simultaneously, preferably in solution, in the aqueous reaction medium which may contain the soluble boron source, in proportions such that the pH of the resulting suspension is between 8.9 and 10.0.

[0056] According to the invention, it is the relative flow rate of the acidic and basic precursors, whether they contain aluminum or not, that is chosen so as to obtain a pH of the reaction medium between 8.9 and 10.0.

[0057] Preferably, the said step(s) a) of precipitation is / are carried out at a pH between 8.9 and 9.8.

[0058] The acidic and basic precursors are also mixed in quantities sufficient to obtain a suspension containing the desired amount of boehmite gel, depending on the final boehmite gel concentration to be achieved. In particular, said step a), or each of the precipitation steps implemented, yields 15 to 100% by weight of boehmite gel in Al₂O₃ equivalent relative to the total amount of boehmite gel formed at the end of the precipitation step(s). According to the invention, the flow rate of the aluminum-containing acidic and basic precursor(s) is adjusted, depending on the duration of step a), so as to obtain a precipitation step a) completion rate of between 15 and 100%, and preferably between 17 and 100%.If the degree of advancement obtained at the end of precipitation step a) is less than 100%, at least a second precipitation step is necessary to increase the amount of boehmite gel formed. When a second precipitation step is implemented, the degree of advancement is defined as the proportion of boehmite gel formed (in Al₂O₃ equivalents) during this second precipitation step relative to the total amount of boehmite gel formed (in Al₂O₃ equivalents) at the end of both precipitation steps of the preparation process according to the invention, and more generally, at the end of all the boehmite gel preparation steps.

[0059] Thus, depending on the target boehmite gel concentration at the end of the precipitation step(s), preferably between 20 and 100 g / l, the quantities of aluminium to be supplied by the acidic and / or basic precursors are calculated and the flow rate of the precursors is adjusted according to the concentration of said precursors in aluminium added, the quantity of water added to the reaction medium and the rate of advancement required for the precipitation step(s).

[0060] If one or more co-precipitation steps are implemented after the first precipitation step, the relative flow rates of the acidic and basic precursors are chosen to achieve a second step completion rate between 0 and 85%, and preferably between 0 and 83%, so that the cumulative completion rate of the first and second precipitation steps is 100%. The relative flow rates of the acidic and basic precursors are chosen to achieve a pH of the reaction medium for the additional precipitation step(s) between 8.9 and 10.0, and preferably between 8.9 and 9.8.

[0061] The flow rates of the aluminum-containing acid and / or basic precursor(s) depend on the size of the reactor used and thus on the amount of water added to the reaction medium.

[0062] Preferably, said step a) and preferably each of the precipitation steps implemented is (are) carried out at a temperature between 20 and 80°C, preferably between 25 and 70°C, more preferably between 30 and 65°C.

[0063] In the case where said preparation process according to the invention comprises two precipitation steps, the precipitation step a) is advantageously carried out at a temperature lower than the temperature of the second precipitation step.

[0064] Preferably, said step a) and preferably each of the precipitation steps implemented is / are carried out for a duration of between 2 and 40 minutes. In the embodiment where several precipitation steps are implemented, preferably, between each precipitation step, a temperature increase may be carried out.

[0065] The said temperature increase can advantageously be carried out at a temperature between 20 and 90°C, preferably between 30 and 80°C, preferably between 30 and 70°C and most preferably between 40 and 65°C.

[0066] In this case, the said intermediate temperature rise is preferably implemented for a period of between 5 and 45 minutes and preferably between 7 and 35 minutes.

[0067] The said intermediate temperature rise is advantageously implemented according to all heating methods known to a person skilled in the art.

[0068] Step b) of heat treatment of the optional suspension

[0069] The said preparation process may optionally include one or more steps b) of heat treatment of the suspension obtained at the end of step a) the said heat treatment step(s) operating at a temperature between 70 and 100°C for a period of between 30 minutes and 5 hours.

[0070] One or more steps b) may advantageously be implemented in the case where only one precipitation step is implemented in the process according to the invention.

[0071] In the case where several precipitation steps a) are implemented, one or more heat treatment steps b) may advantageously be implemented after the last precipitation step a).

[0072] In the event that a heat treatment step of the suspension obtained at the end of step a) is implemented, at least one source of boron, preferably soluble, may optionally be added to the reaction medium during said heat treatment step b).

[0073] The boron source is selected from boric acid (H3BO3), sodium tetraborate decahydrate (Na2B4O·10H2O), sodium metaborate (NaBCh), ammonium pentaborate tetrahydrate ((NH₄BsO₂F₅O), ammonium tetraborate tetrahydrate (H8B4N2O₇H2O), or any other boron salt, alone or in mixture, and preferably from boric acid (H3BO3) and ammonium tetraborate tetrahydrate (H8B4N2O₇H2O), alone or in mixture. All or part of the desired quantity of boron source may advantageously be added in step(s) b), if at least one step b) is carried out. Preferably, the boron source is introduced entirely in step(s) a).

[0074] The quantity of boron source added in said step b) when implemented, is adjusted so that the final alumina obtained comprises a boron element content of between 0.1 and 10% by weight preferably between 0.5 and 9% and even more preferably between 0.8 and 6%, relative to the total weight of said alumina in Al2O3 equivalent.

[0075] Preferably, said heat treatment step b) is a ripening step.

[0076] Preferably, the said heat treatment step(s) b) operate at a temperature between 70 and 100°C and preferably between 70 and 90°C

[0077] Preferably, the said heat treatment step(s) is / are carried out for a period of between 30 minutes and 5 hours.

[0078] This ripening stage is advantageously implemented using all heating methods known to those skilled in the art.

[0079] Step c) of filtration

[0080] According to the invention, the process according to the invention comprises a step c) of filtering the suspension obtained at the end of step a) or optionally at the end of step b) of heat treatment, followed by at least one step of washing the gel obtained. Said filtration step is carried out according to methods known to those skilled in the art.

[0081] The said filtration step is advantageously followed by at least one water washing step and preferably by one to three washing steps, with a quantity of water equal to the quantity of precipitate filtered.

[0082] Step d) drying

[0083] According to the invention, the boehmite gel obtained at the end of step c) of filtration, is dried in a step d) of drying to obtain a powder.

[0084] This drying step is advantageously carried out at a temperature between 20 and 200°C, preferably between 40 and 150°C, and for a duration of between 1 hour and 3 weeks, and preferably between 1 hour and 48 hours, or by spray drying. If this drying step (d) is carried out by spray drying, the cake obtained after the heat treatment step, possibly followed by a filtration step, is resuspended. This suspension is then sprayed as fine droplets into a vertical cylindrical chamber in contact with a stream of hot air to evaporate the water according to the principle well known to those skilled in the art. The resulting powder is carried by the heat flow to a cyclone or baghouse filter, which separates the air from the powder.Preferably, in the case where said drying step d) is implemented by spraying, the spraying is carried out according to the operating protocol described in the publication Asep Bayu Dani Nandiyanto, Kikuo Okuyama, Advanced Powder Technology, 22, 1-19, 2011.

[0085] Boehmite obtained in powder form is advantageously composed of crystallites whose size, obtained by Scherrer's formula in X-ray diffraction along the crystallographic directions (020) and (120) is respectively between 2 and 40 nm and between 2 and 50 nm.

[0086] The boehmite thus prepared makes it easier to shape the said gel according to all the methods known to the person skilled in the art and in particular by mixing extrusion, by granulation and by the technique known as "oil drop" according to Anglo-Saxon terminology.

[0087] Step e) of formatting

[0088] According to the invention, the powder obtained at the end of step d) of drying is shaped in a step e) to obtain a raw material.

[0089] Raw material is defined as material that has been shaped and has not undergone any heat treatment steps.

[0090] Preferably, said shaping step e) is carried out by extrusion mixing, pelletizing, the oil-drop coagulation method, rotary plate granulation or any other method well known to those skilled in the art.

[0091] Preferably, said shaping step e) is carried out by mixing extrusion.

[0092] In a preferred embodiment, said shaping step e) is carried out by mixing-extrusion, said step e) being carried out with a total acid content, expressed as a percentage by weight relative to the mass of dried powder introduced in step e) of between 0 and 10% and a neutralization content expressed as a percentage by weight of base relative to the amount of acid introduced in said step e) of between 0 and 200%.

[0093] Preferably, said step e) is carried out with a total acid content, expressed as a percentage relative to the mass of dried gel introduced in step e) of between 0 and 8%, and most preferably between 0 and 6%, and a neutralization content expressed as a percentage by weight of base relative to the amount of acid introduced in said step e) of between 0 and 150%, preferably between 0 and 130%, most preferably between 0 and 100%, most preferably between 0 and 80%, and most preferably between 0 and 60%.

[0094] Preferably, the acid used in step e) is chosen from nitric acid and carboxylic acids, preferably chosen from acetic acid, citric acid and butyric acid, and preferably nitric acid.

[0095] Preferably, the base used in step e) is chosen from among the inorganic bases selected from sodium hydroxide, potassium hydroxide, and ammonia, and the organic bases in solution selected from among the amines and quaternary ammonium compounds. Preferably, the organic bases in solution are chosen from among the alkylethanolamines and ethoxylated alkylamines. The organic bases are preferably used in aqueous solution.

[0096] Preferably, the said base is ammonia and preferably ammonia in aqueous solution (NH4OH+ H2O).

[0097] According to the invention, the raw material obtained at the end of step e) of shaping, is dried in a step f) of drying carried out at a temperature between 20 and 200°C, preferably between 40 and 150°C and for a period of between 1 hour and 3 weeks and preferably between 1 hour and 48 hours to obtain a dried raw material.

[0098] According to the invention, the dried raw material obtained after drying step f) then undergoes heat treatment step g) at a temperature between 500 and 1000°C for a duration of 1 to 12 hours, with or without an airflow containing up to 60% water by volume. Preferably, said heat treatment step g) is carried out at a temperature between 520 and 850°C, most preferably between 520 and 800°C, and even more preferably between 530 and 750°C.

[0099] Preferably, said heat treatment step g) operates for a duration of between 1h and 12h, preferably between 1h30 and 10h and even more preferably between 2h and 8h.

[0100] Preferably, said step c) is carried out in the presence of an airflow containing a water content of between 5 and 50% by mass, and preferably between 5 and 45% by mass, and preferably between 5 and 40% by mass.

[0101] Said heat treatment step g) allows the transition of boehmite to the final alumina, and allows adjustment of the final porous texture of the alumina prepared according to the invention and which contains Boron.

[0102] The boron content in the material, and preferably in the alumina obtained at the end of step g), is preferably between 0.1 and 10% by weight, more preferably between 0.5 and 9%, even more preferably between 0.8 and 6%, and most preferably between 0.8 and 4.5%, relative to the total weight of said alumina in Al2O3 equivalent. The preparation process according to the invention makes it possible to obtain a mesoporous alumina containing boron and exhibiting controlled mesoporosity, with good thermal and chemical stability, having a centered, uniform, and controlled mesopore size distribution, and a calibrated specific surface area and pore volume, and in particular a calibrated mesopore volume.

[0103] The process according to the present invention allows the production of an alumina comprising boron exhibiting textural properties suitable for its use as a catalyst support.

[0104] The mesoporous alumina containing boron, prepared according to the process of the invention, is preferably free of micropores. The absence of micropores is measured and verified by nitrogen adsorption.

[0105] Preferably, said mesoporous alumina containing boron, prepared according to the process of the invention, is free of macropores. The absence of macropores is measured and verified by mercury porosimetry.

[0106] The mesoporous alumina containing boron, prepared according to the process of the invention and obtained after step g) of heat treatment, advantageously has a specific surface area BET of between 50 and 450 m² 2 / g, preferably between 100 and 400 m 2 / g, preferably between 200 and 400 m 2 / g, and preferably between 220 and 380 m 2 / g and a mesoporous volume greater than or equal to 0.5 ml / g, preferably between 0.55 and 0.85 ml / g, most preferably between 0.60 and 0.80 ml / g and even more preferably between 0.65 and 0.78 ml / g.

[0107] Preferably, the total porous volume of said boron-containing alumina measured by mercury porosimetry is between 0.6 and 0.9 ml / g.

[0108] Preferably, the percentage of volume contained in pores of size between 3 and 50 nm relative to the total pore volume of said boron-containing alumina measured by mercury porosimetry, is greater than 90% and preferably greater than 95%.

[0109] Preferably, the percentage of the mesoporous volume of pores with a diameter between 8 and 20 nm measured by mercury porosimetry is between 60 and 100%, preferably between 65 and 100%.

[0110] The average diameter of the mesopores measured by mercury porosimetry of said boron-containing alumina, determined by volume, is advantageously between 7 and 13.5 nm and preferably between 8.5 and 12.5 nm, most preferably between 9.0 and 12.3 nm, even more preferably between 9.5 and 12.0 nm.

[0111] Preferably, the boron content in the alumina obtained at the end of step g) is between 0.1 and 10% by weight, preferably between 0.5 and 9% and even more preferably between 0.8 and 6%, relative to the total weight of said alumina in Al2O3 equivalent.

[0112] Preferably, the alumina according to the invention is a non-mesostructured alumina.

[0113] The mesoporous alumina containing boron has a sulfur content advantageously between 0.001% and 0.4% by weight and a sodium content advantageously between 0.001% and 0.04% by weight, the weight percentages being expressed relative to the total mass of boehmite gel in its Al2O3 form. Preferably, the boron-containing alumina obtained at the end of the process according to the invention is in the form of irregular and non-spherical beads, extrudates, pellets or agglomerates whose specific shape may result from a crushing step.

[0114] Preferably, the boron-containing alumina prepared according to the invention is used as a catalyst support. The support comprising the boron-containing alumina takes the form of extrudates with a diameter between 0.8 and 3 mm, preferably between 1.2 and 2.6 mm. The geometry of the extrudates can be cylindrical, trilobular, quadrilobular, or any other advantageous shape depending on the desired application.

[0115] A catalyst can advantageously be prepared from boron-containing alumina prepared according to the invention and used as a support for said catalyst.

[0116] One or more elements chosen in relation to the desired catalytic application are then deposited on the surface of said support according to any method known to a person skilled in the art.

[0117] The process according to the invention may advantageously include a step (h) of deposition onto said boron-containing alumina obtained from step (g) of at least one metal from Group VIII and / or at least one metal from Group VIB of the periodic table of elements, optionally a dopant element selected from boron, phosphorus, and silicon, and preferably phosphorus, and optionally at least one organic additive. If an organic additive is deposited, its deposition is followed by a drying step without calcination. If no organic additive has been deposited, the metal deposition is followed by a drying step and optionally a calcination step.

[0118] The metal(s) of group VIII and / or at least one metal of group VI B may advantageously be introduced in one or more stages and preferably by dry or excess impregnation.

[0119] In a preferred mode, at least one metal from group VIII, at least one metal from group VIB, at least one dopant selected from phosphorus and silicon and preferably phosphorus, and possibly at least one organic additive are deposited on said support.

[0120] The metal from group VIB present in the active phase of the catalyst is preferably chosen from molybdenum and tungsten. The metal from group VIII present in the active phase of the catalyst is preferably chosen from cobalt, nickel, and mixtures of these two elements. The active phase of the catalyst is preferably chosen from the group formed by the combination of nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, nickel-molybdenum-tungsten, and nickel-cobalt-molybdenum, and most preferably the active phase consists of nickel and molybdenum, nickel and tungsten, or a nickel-molybdenum-tungsten combination.

[0121] The content of group VIII metal in the catalyst is less than 20% by weight, preferably between 0.03 and 15% by weight, most preferably between 0.5 and 10% by weight, and even more preferably between 1 and 8% by weight expressed as group VIII metal oxide relative to the total weight of the catalyst.

[0122] The content of group VI B metal in the catalyst is between 1 and 50% by weight, preferably between 5 and 40% by weight, more preferably between 10 and 35% by weight and even more preferably between 15 and 30% by weight expressed as group VI B metal oxide relative to the total weight of the catalyst.

[0123] The molar ratio of Group VIII metal to Group VI B metal of the catalyst is generally less than 1, preferably between 0.01 and 0.75, and most preferably between 0.10 and 0.60 and even more preferably between 0.20 and 0.50.

[0124] Optionally, the catalyst may also have a phosphorus content generally less than 15% by weight, preferably between 0.1 and 10% by weight, most preferably between 0.1 and 8% by weight, and even more preferably between 0.2 and 6% by weight of P2O5 relative to the total weight of fresh catalyst.

[0125] Furthermore, in the case where the catalyst includes phosphorus, the phosphorus / (metal of group VIB) molar ratio is generally between 0.02 and 1, preferably between 0.04 and 0.8, and most preferably between 0.1 and 0.75.

[0126] The catalyst may also include at least one additional organic compound containing oxygen and / or nitrogen and / or sulfur before sulfidation. Such additives are known to those skilled in the art. Generally, the organic compound is chosen from among compounds containing one or more chemical functionalities selected from a carboxyl group, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide, or compounds including a furan ring, or sugars.

[0127] The content of organic compound(s) containing oxygen and / or nitrogen and / or sulfur in the catalyst is between 1 and 30% by weight, preferably between 1.5 and 25% by weight, and more preferably between 2 and 20% by weight, relative to the total weight of the fresh catalyst. The organic compound(s) introduced during any of the catalyst preparation steps are introduced in a quantity corresponding to:

[0128] - to a compound molar ratio added by group VI B metal(s) present in the regenerated catalyst of between 0.01 and 2.0 mol / mol, preferably between 0.01 and 1.5 mol / mol, preferably between 0.01 and 1.0 mol / mol, and most preferably between 0.02 and 0.8 mol / mol,

[0129] - and to a compound molar ratio added by group VIII metal(s) present in the regenerated catalyst of between 0.02 and 6.0 mol / mol, preferably between 0.03 and 4.0 mol / mol, preferably between 0.04 and 3.0 mol / mol, and most preferably between 0.05 and 0.4 mol / mol.

[0130] When several compounds are present, the different molar ratios are added together so that the sum of the added compounds corresponds to the values ​​above.

[0131] The oxygen-containing organic compound may be one or more of a carboxylic acid, an alcohol, an aldehyde, or an ester. For example, the oxygen-containing organic compound may be one or more of the following: ethylene glycol, glycerol, polyethylene glycol, acetophenone, 2,4-pentanedione, pentanole, acetic acid, maleic acid, oxalic acid, tartaric acid, formic acid, citric acid, and C1-C4 dialkyl succinate. When the organic compound is a carboxylic organic acid, it is preferably chosen from acetic acid, maleic acid, malic acid, malonic acid, gluconic acid, tartaric acid, citric acid, γ-ketovaleric acid, lactic acid, pyruvic acid, ascorbic acid, oxalic acid or succinic acid,

[0132] According to one variant of the invention, when an organic compound is present, the fresh catalyst has not undergone calcination during its preparation, i.e. the impregnated catalytic precursor has not been subjected to a heat treatment step at a temperature above 200°C under an inert atmosphere or under an atmosphere containing oxygen, in the presence of water or not.

[0133] Another object of the present invention is a hydrotreating process for hydrocarbon cuts using a catalyst containing an alumina comprising boron, said alumina being prepared according to the preparation process according to the invention.

[0134] In particular, another object of the present invention is a hydrotreating process for feedstocks selected from hydrocarbon fractions having a distillation range between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks selected from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in mixtures, and feedstocks from the reprocessing of biomass and / or plastics and / or tires and / or household waste, alone or in mixtures, said process employing a catalyst comprising at least one metal from group VIII, at least one metal from group VIB, optionally at least one dopant selected from boron,phosphorus and silicon, and preferably phosphorus and optionally at least one organic additive and a support comprising, and preferably consisting of, said alumina comprising boron according to the invention or prepared according to the preparation process according to the invention.

[0135] Before its use in a hydrocarbon fraction hydrotreating process, the catalyst is generally subjected to sulfidation to obtain the metals in their sulfided or partially sulfided forms as described below. This activation or sulfidation step is carried out using methods well known to those skilled in the art, and advantageously under a sulfur-reducing atmosphere in the presence of hydrogen and hydrogen sulfide.

[0136] The catalyst is advantageously sulfided ex situ or in situ. Sulfurizing agents include hydrogen sulfide (H₂S), elemental sulfur, CS₂, mercaptans, sulfides and / or polysulfides, hydrocarbon fractions with a boiling point below 400°C containing sulfur compounds, or any other sulfur-containing compound used for activating hydrocarbon feedstocks to sulfidate the catalyst. These sulfur-containing compounds are advantageously selected from alkyl disulfides, such as dimethyl disulfide (DMDS), alkyl sulfides, such as dimethyl sulfide, thiols, such as n-butylmercaptan (or 1-butanethiol), and polysulfide compounds of the tertiononyl polysulfide type. The catalyst can also be sulfided with sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfided in situ in the presence of a sulfurizing agent and a hydrocarbon feedstock.Preferably the catalyst is sulfided in situ in the presence of a hydrocarbon feed supplemented with dimethyl disulfide.

[0137] Use of a catalyst prepared from a support prepared according to the invention

[0138] Preferably, heavy hydrocarbon feedstocks are selected from those with a weighted average temperature (WAT) above 380°C. WAT is defined as the distillation temperatures of 5%, 50%, and 70% of the feed volume using the following formula: WAT = (T 5% + 2 x T 50% + 4 x T 70%) / 7. WAT is calculated from simulated distillation values. The WAT of the feed is above 380°C and preferably below 600°C, and even more preferably below 580°C.

[0139] According to the invention, the treated hydrocarbon feedstock preferably has a distillation range between 250°C and 600°C, preferably between 300 and 580°C.

[0140] The said hydrocarbon feedstock is advantageously chosen from LCOs or HCOs (Light Cycle Oil or Heavy Cycle Oil according to Anglo-Saxon terminology (light or heavy gas oils from a catalytic cracking unit)), vacuum distillates for example gas oils from the direct distillation of crude or from conversion units such as catalytic cracking, coker or visbreaking, feedstocks from aromatic extraction units, lubricating oil bases or from solvent dewaxing of lubricating oil bases, distillates from desulfurization or hydroconversion processes in fixed bed or bubbling bed of atmospheric residues and / or vacuum residues and / or deasphalted oils, or the feedstock may be a deasphalted oil.

[0141] Preferably, said hydrocarbon charge is a vacuum distillate.

[0142] Any hydrocarbon feed containing sulfur and nitrogen compounds that inhibit hydrotreating, and with a TMP similar to that of a vacuum distillate cut, can be used in the process of the present invention. The hydrocarbon feed can be of any chemical nature, that is, it can have any distribution among the different chemical families, including paraffins, olefins, naphthenes, and aromatics. This hydrocarbon feed comprises nitrogenous and / or sulfurous organic molecules. The nitrogenous organic molecules are either basic, such as amines, anilines, pyridines, acridines, quinolines, and their derivatives, or neutral, such as pyrroles, indoles, carbazoles, and their derivatives. It is primarily the basic nitrogenous molecules that inhibit hydrotreating catalysts, particularly additive catalysts.

[0143] The nitrogen content is greater than or equal to 250 ppm, preferably between 400 and 10,000 ppm by weight, more preferably between 700 and 4,000 ppm by weight, and even more preferably between 1,000 and 4,000 ppm by weight. The basic nitrogen content comprises at least one-quarter of the total nitrogen content. The basic nitrogen content is generally greater than or equal to 60 ppm, more preferably between 175 and 1,000 ppm by weight, and even more preferably between 250 and 1,000 ppm by weight. The sulfur content in the feedstock is generally between 0.01 and 5% by weight, preferably between 0.2 and 4% by weight, and even more preferably between 0.5 and 3% by weight.

[0144] The hydrocarbon feedstock may advantageously contain metals, in particular nickel and vanadium. The cumulative nickel and vanadium content of the hydrocarbon feedstock, treated according to the hydrocracking process of the invention, is preferably less than 1 ppm by weight.

[0145] The asphaltene content of said hydrocarbon feedstock is generally less than 3000 ppm, preferably less than 1000 ppm, even more preferably less than 200 ppm.

[0146] The processed feedstock generally contains resins, preferably with a resin content greater than 1% wt. Resin content is measured according to ASTM D 2007-11.

[0147] According to the invention, said feed treated in the hydrotreatment process is chosen from renewable feeds selected from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in mixtures, and feeds from the reprocessing of biomass / plastics / tires / and household waste, alone or in mixtures.

[0148] The said charge treated according to the hydrotreating process of the invention may also be a mixture of the said charges previously mentioned.

[0149] The catalyst prepared from the boron-containing alumina support according to the invention can then be used in one, two, or more reactors. It is generally used for fixed-bed implementation.

[0150] The operating conditions used for the operation, preferably in a fixed bed, of the catalyst prepared from the alumina support containing boron according to the invention correspond to those generally used for a hydrotreating process and are as follows: the temperature is advantageously between 200 and 450°C, and preferably between 300 and 400°C; the pressure is advantageously between 0.5 and 30 MPa, and preferably between 5 and 20 MPa; the hourly volumetric rate (defined as the ratio of the volumetric feed rate to the volume of the catalyst per hour) is advantageously between 0.1 and 20 h -1 and preferably between 0.2 and 5 hours 1 , and the hydrogen / charge ratio expressed in volume of hydrogen, measured under normal temperature and pressure conditions, per volume of liquid charge is advantageously between 50 l / l and 2000 l / l.

[0151] The invention is illustrated by the following examples, which are in no way intended to be limiting.

[0152] Examples:

[0153] Example 1 according to the invention (addition of 1% Boron, source: ammonium tetraborate tetrahydrate (H8B4N2O7 H2O)):

[0154] The preparation of alumina is carried out according to a preparation process conforming to the invention in a 5 L reactor in two precipitation stages with the addition of boron salt to the water base. Agitation is maintained at 350 rpm throughout the synthesis.

[0155] The final concentration of boehmite gel considered in the target form Al2O3 is 38.4 g / l. The quantity of water added to the reactor before the first co-precipitation (water foot) is 2457 mL water and it contains 30.7 g of ammonium tetraborate tetrahydrate (H8B4N2O7 H2O).

[0156] A first co-precipitation step in water, involving the simultaneous addition of aluminum sulfate Ah(SO4) and sodium aluminate NaAlOO, is carried out at 40°C and pH=9.4 for a duration of 8 minutes. The concentrations of the aluminum precursors used are as follows: Ah(SO4)3 at 102 g / l as Al2O3 and NaAlOO at 155 g / l as Al2O3.

[0157] An aluminum sulfate solution (Ah(SO4)3) is continuously added to the reactor containing water for 8 minutes at a rate of 12.5 mL / min, simultaneously with a sodium aluminate solution (NaAlOO) at a rate of 18.8 mL / min, to adjust the pH to 9.4. The reaction temperature is maintained at 40°C. A suspension containing a Boehmite gel precipitate is obtained. The first precipitation step is 25% complete. The resulting suspension is then heated from 40 to 60°C over 30 minutes.

[0158] A second co-precipitation step of the resulting suspension is then carried out by the simultaneous addition of aluminum sulfate Al₂(SO₄)₃ at a concentration of 102 g / L Al₂O₃ and sodium aluminate NaAlOO₄ at a concentration of 155 g / L Al₂O₃. An aluminum sulfate solution Ah(SO₄)₃ is therefore continuously added to the heated suspension obtained after the first precipitation step for 30 minutes at a rate of 10 mL / min, simultaneously with a sodium aluminate solution NaAlOO₄ at a rate of 15 mL / min, in order to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second step is maintained at 60°C.

[0159] These flow rates of acidic and basic precursors containing aluminum allow for a 75% advancement rate at the end of the second precipitation stage, with the cumulative advancement rate of the first and second precipitation stages being 100%. A suspension containing a boehmite gel precipitate containing boron is obtained.

[0160] The resulting suspension is then filtered by water displacement over a sintered Buchner type tool and the resulting alumina gel is washed 3 times with 5 L of distilled water.

[0161] The characteristics of the boehmite gel thus obtained are summarized in Table 1.

[0162] Table 1: Characteristics of the boehmite gel obtained according to example 1 determined by XRD.

[0163] Table 1

[0164] The boron-containing boehmite gel obtained according to Example 1 was dried in a ventilated study at 120°C for 16 hours.

[0165] The dried boehmite gel is then introduced into a Brabender-type mixer. Acidified water with nitric acid, at a total acid concentration of 4% (expressed by weight relative to the mass of dried powder, considered as Al₂O₃), is added over 5 minutes during mixing at 20 rpm. Acid mixing continues for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer at a neutralization concentration of 40% (expressed by weight of ammonia relative to the amount of nitric acid introduced for the acidification step). Mixing continues for 3 minutes.

[0166] The resulting paste is then extruded through a 2 mm trilobed die. The extrudates are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under a stream of air containing no water. The alumina obtained exhibits the characteristic peaks of gamma alumina in X-ray diffraction. The textural characteristics of the boron-containing gamma alumina formed are shown in Table 2: Table 2: Characteristics of boron-containing alumina A obtained according to Example 1.

[0167] Table 2 Example 2 according to the invention (addition of 1% Boron, source: ammonium tetraborate tetrahydrate (H8B4N2O7 H2O)):

[0168] The paste obtained in Example 1 is extruded through a 2 mm trilobed die. The resulting extrudates are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under a stream of air containing 20% ​​water by volume. The alumina obtained exhibits the characteristic peaks of gamma alumina in X-ray diffraction. The textural characteristics of the boron-containing gamma alumina formed are reported in Table 3.

[0169] Table 3: Characteristics of boron-containing alumina B obtained according to example 2.

[0170] Table 3

[0171] Example 3 according to the invention (addition of 2% boron, source: ammonium tetraborate tetrahydrate (H8B4N2O7 H2O)): Alumina is prepared according to a preparation process according to the invention with the addition of the boron salt to the water base. Agitation is maintained at 350 rpm throughout the synthesis.

[0172] The synthesis of boehmite gel is carried out according to a preparation process according to the invention in a 5 L reactor in two precipitation stages.

[0173] The final concentration of boehmite gel considered in the target form Al2O3 is 38.4 g / l. The quantity of water added to the reactor before the first co-precipitation (water foot) is 2457 mL water and it contains 61.4 g of ammonium tetraborate tetrahydrate (H8B4N2O7*4H2O).

[0174] A first co-precipitation step in water, involving the simultaneous addition of aluminum sulfate Al2(SO4) and sodium aluminate NaAlOO, is carried out at 40°C and pH=9.4 for a duration of 8 minutes. The concentrations of the aluminum precursors used are as follows: Al2(SC>4)3 at 102 g / l as Al2O8 and NaAlOO at 155 g / l as Al2O3.

[0175] An aluminum sulfate (Al₂(SO₄)₃ solution is continuously added to the reactor containing water for 8 minutes at a rate of 11.3 mL / min, simultaneously with a sodium aluminate (NaAlOO₄) solution at a rate of 21.9 mL / min, to adjust the pH to 9.4. The reaction temperature is maintained at 40°C. A suspension containing a Boehmite gel precipitate is obtained. The first precipitation step is 25% complete. The resulting suspension is then heated from 40 to 60°C over 30 minutes.

[0176] A second co-precipitation step of the resulting suspension is then carried out by the simultaneous addition of aluminum sulfate Al₂(SO₄)₃ at a concentration of 102 g / L Al₂O₃ and sodium aluminate NaAlOO₄ at a concentration of 155 g / L Al₂O₃. An aluminum sulfate Al₂(SO₄)₃ solution is therefore continuously added to the heated suspension obtained after the first precipitation step for 30 minutes at a rate of 9.8 mL / min, simultaneously with a sodium aluminate NaAlOO₄ solution at a rate of 17 mL / min, in order to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second step is maintained at 60°C.

[0177] These flow rates of acidic and basic precursors containing aluminum allow for a 75% advancement rate at the end of the second precipitation stage, with the cumulative advancement rate of the first and second precipitation stages being 100%. A suspension containing a boehmite gel precipitate containing boron is obtained.

[0178] The resulting suspension is then filtered by water displacement through a sintered Buchner funnel, and the alumina gel is washed three times with 5 L of distilled water. The characteristics of the boehmite gel thus obtained are summarized in Table 4.

[0179] Table 4: Characteristics of the boehmite gel obtained according to example 3 determined by XRD.

[0180] Table 4

[0181] The boron-containing boehmite gel obtained according to Example 3 was dried in a ventilated study at 120°C for 16 hours.

[0182] The dried boehmite gel is then introduced into a Brabender-type mixer. Acidified water with nitric acid, at a total acid concentration of 4% (expressed by weight relative to the mass of dried powder, considered as Al₂O₃), is added over 5 minutes during mixing at 20 rpm. Acid mixing continues for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer at a neutralization concentration of 40% (expressed by weight of ammonia relative to the amount of nitric acid introduced for the acidification step). Mixing continues for 3 minutes.

[0183] The resulting paste is then extruded through a 2 mm trilobed die. The extrudates are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under a stream of water-free air. The alumina produced exhibits the characteristic peaks of gamma alumina in X-ray diffraction. The textural characteristics of the boron-containing gamma alumina formed are reported in Table 5.

[0184] Table 5: Characteristics of boron-containing alumina C obtained according to example 3.

[0185] Table 5 Example 4 according to the invention (addition of 2% boron, source: boric acid (H3BO3)) Alumina is prepared according to a process according to the invention in a 5 L reactor in two precipitation stages with the addition of boron salt to the water base. Agitation is maintained at 350 rpm throughout the synthesis.

[0186] The final concentration of boehmite gel considered in the target form Al2O3 is 38.4 g / l. The quantity of water added to the reactor before the first co-precipitation (water foot) is 2460 mL water and it contains 14.41 g of boric acid (H3BO3).

[0187] A first co-precipitation step in water, involving the simultaneous addition of aluminum sulfate Al2(SC>4) and sodium aluminate NaAlOO, is carried out at 40°C and pH=9.4 for a duration of 8 minutes. The concentrations of the aluminum precursors used are as follows: Al2(SO4)3 at 102 g / l as Al2Os and NaAlOO at 155 g / l as Al2O3.

[0188] An aluminum sulfate (Al₂(SO₄)₃ solution is continuously added to the reactor containing water for 8 minutes at a rate of 13.8 mL / min, simultaneously with a sodium aluminate (NaAlOO₄) solution at a rate of 21.9 mL / min, to adjust the pH to 9.4. The reaction temperature is maintained at 40°C. A suspension containing a Boehmite gel precipitate is obtained. The first precipitation step is 25% complete. The resulting suspension is then heated from 40 to 60°C over 30 minutes.

[0189] A second co-precipitation step of the resulting suspension is then carried out by the simultaneous addition of aluminum sulfate Al₂(SO₄)₃ at a concentration of 102 g / L Al₂O₃ and sodium aluminate NaAlOO₄ at a concentration of 155 g / L Al₂O₃. An aluminum sulfate Al₂(SO₄)₃ solution is therefore continuously added to the heated suspension obtained after the first precipitation step for 30 minutes at a rate of 10.3 mL / min, simultaneously with a sodium aluminate NaAlOO₄ solution at a rate of 15.8 mL / min, in order to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second step is maintained at 60°C.

[0190] These flow rates of acidic and basic precursors containing aluminum allow for a 75% advancement rate at the end of the second precipitation stage, with the cumulative advancement rate of the first and second precipitation stages being 100%. A suspension containing a boehmite gel precipitate containing boron is obtained.

[0191] The resulting suspension is then filtered by water displacement over a sintered Buchner type tool and the resulting alumina gel is washed 3 times with 5 L of distilled water.

[0192] The characteristics of the boehmite gel thus obtained are summarized in Table 6. Table 6: Characteristics of the boehmite gel obtained according to example 4 determined by XRD.

[0193] Table 6

[0194] The boron-containing boehmite gel obtained according to Example 4 was dried in a ventilated study at 120°C for 16 hours.

[0195] The dried boehmite gel is then introduced into a Brabender-type mixer. Acidified water with nitric acid, at a total acid concentration of 4% (expressed by weight relative to the mass of dried powder, considered as Al₂O₃), is added over 5 minutes during mixing at 20 rpm. Acid mixing continues for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer at a neutralization concentration of 40% (expressed by weight of ammonia relative to the amount of nitric acid introduced for the acidification step). Mixing continues for 3 minutes.

[0196] The resulting paste is then extruded through a 2 mm trilobed die. The extrudates are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under a stream of water-free air. The alumina produced exhibits the characteristic peaks of gamma alumina in X-ray diffraction. The textural characteristics of the boron-containing gamma alumina formed are reported in Table 7.

[0197] Table 7: Characteristics of boron-containing alumina D obtained according to example 4.

[0198] Table 7 Example 5 according to the invention (addition of 4% boron, source: boric acid (H3BO3)) Alumina is prepared according to a process according to the invention in a 5 L reactor in two precipitation stages with the addition of boron salt to the water base. Agitation is maintained at 350 rpm throughout the synthesis.

[0199] The final concentration of boehmite gel considered in the target form Al2O3 is 38.4 g / l. The quantity of water added to the reactor before the first co-precipitation (water foot) is 2450 mL water and it contains 28.83 g of boric acid (H3BO3).

[0200] A first co-precipitation step in water, involving the simultaneous addition of aluminum sulfate Al2(SC>4) and sodium aluminate NaAlOO, is carried out at 40°C and pH=9.4 for a duration of 8 minutes. The concentrations of the aluminum precursors used are as follows: Al2(SO4)3 at 102 g / l as Al2Os and NaAlOO at 155 g / l as Al2O3.

[0201] An aluminum sulfate (Al₂(SO₄)₃ solution is continuously added to the reactor containing water for 8 minutes at a rate of 13.1 mL / min, simultaneously with a sodium aluminate (NaAlOO₄) solution at a rate of 20.0 mL / min, to adjust the pH to 9.4. The reaction temperature is maintained at 40°C. A suspension containing a Boehmite gel precipitate is obtained. The first precipitation step is 25% complete. The resulting suspension is then heated from 40 to 60°C over 30 minutes.

[0202] A second co-precipitation step of the resulting suspension is then carried out by the simultaneous addition of aluminum sulfate Al₂(SO₄)₃ at a concentration of 102 g / L Al₂O₃ and sodium aluminate NaAlOO₄ at a concentration of 155 g / L Al₂O₃. An aluminum sulfate Al₂(SO₄)₃ solution is therefore continuously added to the heated suspension obtained after the first precipitation step for 30 minutes at a rate of 9.7 mL / min, simultaneously with a sodium aluminate NaAlOO₄ solution at a rate of 14.3 mL / min, in order to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second step is maintained at 60°C.

[0203] These flow rates of acidic and basic precursors containing aluminum allow for a 75% advancement rate at the end of the second precipitation stage, with the cumulative advancement rate of the first and second precipitation stages being 100%. A suspension containing a boehmite gel precipitate containing boron is obtained.

[0204] The resulting suspension is then filtered by water displacement over a sintered Buchner type tool and the resulting alumina gel is washed 3 times with 5 L of distilled water.

[0205] The characteristics of the boehmite gel thus obtained are summarized in Table 8. Table 8: Characteristics of the boehmite gel obtained according to example 5 determined by XRD.

[0206] Table 8

[0207] The boron-containing boehmite gel obtained according to Example 5 was dried in a ventilated study at 120°C for 16 hours.

[0208] The dried boehmite gel is then introduced into a Brabender-type mixer. Acidified water with nitric acid, at a total acid concentration of 4% (expressed by weight relative to the mass of dried powder, considered as Al₂O₃), is added over 5 minutes during mixing at 20 rpm. Acid mixing continues for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer at a neutralization concentration of 40% (expressed by weight of ammonia relative to the amount of nitric acid introduced for the acidification step). Mixing continues for 3 minutes.

[0209] The resulting paste is then extruded through a 2 mm trilobed die. The extrudates are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under a stream of air containing no water. The alumina obtained exhibits the characteristic peaks of gamma alumina in X-ray diffraction. The textural characteristics of the boron-containing gamma alumina formed are reported in Table 9.

[0210] Table 9: Characteristics of boron-containing alumina E obtained according to example 5.

[0211] Table 9 Example 6 comparative to example 1 of US patent 4724226

[0212] The preparation of alumina is carried out according to a preparation process conforming to example 1 of US patent 4724226A. The stirring is at 350 rpm throughout the synthesis.

[0213] The synthesis of boehmite gel is carried out according to a preparation process according to the invention in a 5 L reactor in two precipitation stages.

[0214] The amount of water added to the reactor before co-precipitation (water foot) is 1500 mL water. 900 mL of a 7% Al₂(SO₄)₃ aluminum sulfate solution is continuously added to the reactor containing water, simultaneously with 600 mL of a 23% Al₂O₃ sodium aluminate solution (NaAlOO₄) and 400 mL of a solution containing 39.5 g of sodium metaborate (Na₂B₂O₄) at a flow rate of 20.0 mL / min to adjust the pH to 7.4. The reaction temperature is maintained at 65°C. A suspension containing a boehmite gel precipitate is obtained. The resulting suspension is then water-displacement filtered through a sintered Buchner funnel, and the alumina gel is washed with 20 L of distilled water and dried overnight under vacuum at 100°C.

[0215] The dried gel is extruded through a 1.6 mm die and calcined for 2 h at 760°C under a flow of air containing no water.

[0216] The textural characteristics of the alumina formed containing boron are reported in Table 10:

[0217] Table 10: Characteristics of boron-containing alumina F obtained according to example 6.

[0218] Table 10

[0219] Example 7: Catalysts prepared with supports A to F

[0220] Supports A to F were dry-impregnated with an aqueous nickel-molybdenum solution, targeting molybdenum and nickel contents of 28% wt. and 6.55% wt., respectively, expressed as oxides, corresponding to a theoretical molar ratio of 0.45. After a 6-hour curing period in a closed system, the extrudates were dried at 120°C for 1 hour before being dry-impregnated again with a solution of an organic additive, succinic acid. A final drying process was then applied to the extrudates for one hour in air at 120°C.

[0221] Catalysts 1 to 6, respectively obtained, were then evaluated by hydrodeazotation of a vacuum distillate with a melting point (TM P) of 474°C (T5% = 389°C, T50% = 468°C, T70% = 498°C). The feed characteristics are as follows: sulfur 2.6 wt%, nitrogen 1350 ppm, basic nitrogen 392 ppm, resins 9.1 wt%.

[0222] The test is conducted in a pilot isothermal flow-through fixed-bed reactor, with fluids flowing from bottom to top.

[0223] After in situ sulfidation at 350 °C in the pressurized unit using the vacuum distillate of the test to which 2% by weight of dimethyl disulfide is added, the hydrotreating test was carried out under the following operating conditions: a total pressure of 16 MPa, a WH of 1.5 h-1, an H2 / charge ratio of 1000 l / h and a temperature of 370°C.

[0224] Table 11 shows the relative HDN percentage achieved in the reactor. The HDN percentage is calculated as follows: HDN (%) = (Nout - Nin) / Nin. The relative HDN % is normalized to a base of 100, corresponding to the reference case without boron.

[0225] Table 11 The following examples demonstrate that an alumina prepared according to the invention and containing an amount of boron preferably between 0.8 and 4.5% and in particular in which the boron source is introduced during precipitation (supports 1 to 6) makes it possible to obtain aluminas with specific textural characteristics.

[0226] Furthermore, the examples provided highlight the interest of these textural distributions combined with the presence of boron since the hydrodeazotation performance of distillate feeds under vacuum, of catalysts prepared identically from the various supports are significantly higher with catalysts 1 to 5 prepared according to the invention than with the non-conforming catalyst 6 which contains an amount of boron less than 0.8% nor the desired textural characteristics.

Claims

DEMANDS 1. A process for preparing boron-containing alumina, said process comprising at least the following steps: a) at least one or more steps of precipitating a boehmite gel, in an aqueous reaction medium, by the simultaneous addition of at least one basic precursor selected from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulfate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of the basic or acid precursors comprises aluminum, the relative flow rates of the acidic and basic precursors being selected to obtain a pH of the reaction medium between 8.9 and 10,0 and the flow rate of the aluminum-containing acid and basic precursor(s) is adjusted to obtain a rate of advancement of said first step between 15 and 100% and preferably between 17 and 100%, the rate of advancement being defined as the proportion of boehmite gel formed in Al2O3 equivalent during said first precipitation step relative to the total quantity of boehmite gel formed in Al2O3 equivalent at the end of the precipitation step(s) implemented, said precipitation step operating at a temperature between 20 and 80°C, and for a duration between 2 minutes and 30 minutes, b) optionally one or more heat treatment step(s) of the suspension obtained at the end of step a) at a temperature between 70 and 100°C for a duration between 30 minutes and 5 hours,c) a filtration step of the suspension obtained at the end of heat treatment step a) or possibly at the end of step b), followed by at least one washing step of the boehmite gel obtained, d) a drying step of the boehmite gel obtained at the end of step c) to obtain a powder, e) a shaping step of the powder obtained at the end of step d) to obtain the raw material, f) a drying step of the raw material obtained in shaping step e), carried out at a temperature between 20 and 200°C and for a duration between 1 hour and 3 weeks to obtain a dried raw material, g) a heat treatment step of the dried raw material obtained at the end of step f) at a temperature between 500 and 1000°C, and for a duration between 1 and 12 hours in the presence or absence of an airflow containing up to 60% by volume of water, to obtain said alumina containing boron, said process being characterized in that at least one source of boron is added in at least one or more of said step(s) a) of precipitation and / or optionally in said step(s) b) of heat treatment in the case where one or more step b) is / are implemented.

2. A process according to claim 1 wherein said boron source is selected from boric acid (H3BO3), sodium tetraborate decahydrate (Na2B4O?*10H2O), sodium metaborate (NaBC>2), ammonium pentaborate tetrahydrate ((NH^BsOs W), ammonium tetraborate tetrahydrate (H8B4N2O7 H2O) or any other boron salt, alone or in mixture and preferably from boric acid (H3BO3) and ammonium tetraborate tetrahydrate (H8B4N2O7 H2O), alone or in mixture.

3. A process according to claim 1 or claim 2 wherein the boron source is added to the aqueous reaction medium in aqueous solution before the simultaneous addition of the basic aluminum precursor and the acid aluminum precursor, without having been previously mixed with either of said acid or basic aluminum precursors.

4. A method according to any one of the preceding claims, wherein in the case where said method comprises several precipitation steps a) the boron source is added, in part, in each of the precipitation steps carried out and preferably in full in the first precipitation step.

5. A process according to any one of the preceding claims in which said precipitation step(s) a) is / are carried out at a pH between 8.9 and 9.

8.

6. A method according to any one of the preceding claims in which said shaping step e) is carried out by mixing extrusion.

7. A method according to any one of claims 1 to 6, wherein a step h) of deposition of at least one metal from group VIII and / or at least one metal from group VIB of the periodic table of elements, optionally at least one dopant element selected from boron, phosphorus and silicon and preferably phosphorus and possibly at least one organic additive, on said boron-containing alumina from step g) is implemented.

8. Mesoporous alumina containing boron obtained according to the process of claims 1 to 7, wherein the boron content in the alumina obtained at the end of step g) of the process according to claims 1 to 7 is between 0.1 and 10% wt%, preferably between 0.5 and 9%, and even more preferably between 0.8 and 6%, relative to the total weight of said alumina in Al2O3 equivalent, and said alumina having a specific surface area BET of between 50 and 450 m2 / g, preferably between 100 and 400 m 2 / g, preferably between 200 and 400 m 2 / g, and preferably between 220 and 380 m 2 / g, a total pore volume measured by mercury porosimetry of between 0.6 and 0.9 ml / g, a mesoporous volume greater than or equal to 0.5 ml / g, preferably between 0.55 and 0.85 ml / g, most preferably between 0.60 and 0.80 ml / g and even more preferably between 0.65 and 0.78 ml / g, a percentage of volume within pores of size between 3 and 50 nm relative to the total pore volume measured by mercury porosimetry, greater than 90%, a percentage of the mesoporous volume of pores having a diameter between 8 and 20 nm measured by mercury porosimetry of between 60 and 100% and a mean diameter of mesopores measured by mercury porosimetry, determined in volume, of between 7 and 13.5 nm and preferably between 8.5 and 12.5 nm, very preferably between 9.0 and 12.3 nm, even more preferably between 9.5 and 12.0 nm.

9. A hydrotreating process for feedstocks selected from hydrocarbon cuts having a distillation range between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks selected from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in mixtures, and feedstocks from the reprocessing of biomass and / or plastics and / or tires and / or household waste, alone or in mixtures, said process employing a catalyst comprising at least one metal from group VIII, at least one metal from group VIB, optionally at least one dopant selected from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive and a support comprising and preferably consisting of said alumina comprising boron according to claim 8 or prepared according to the preparation process according to any one of claims 1 to 7.

10. A process according to claim 9, wherein the temperature of the hydrotreating process is between 200 and 450°C, and preferably between 300 and 400°C, the pressure is between 0.5 and 30 MPa, and preferably between 5 and 20 MPa, and the hourly volumetric velocity, defined as the ratio of the volumetric feed flow rate to the volume of catalyst per hour, is between 0.1 and 20 h -1 and preferably between 0.2 and 5 hours 1 , and the hydrogen / charge ratio expressed in volume of hydrogen, measured under normal temperature and pressure conditions, per volume of liquid charge is between 50 l / l and 2000 l / l.

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