PROCESS FOR PREPARING AN ALUMINA COMPRISING TITANIUM FOR THE HYDROTREATMENT OF HYDROCARBON FEEDS

Abstract

The present invention relates to the preparation of a mesoporous titanium-containing alumina shaped from a boehmite gel in which at least one titanium precursor is added in the step of precipitating at least one aluminum salt to form a boehmite gel and / or in the step of shaping the boehmite gel obtained. The titanium-containing alumina according to the invention, due to its advantageous properties, can be used as a catalyst support in all refining processes as well as an adsorbent, in particular for catalytic processes treating hydrocarbon cuts such as the hydrotreatment of vacuum distillates.

Description

Title of the invention: PROCESS FOR PREPARING AN ALUMINA COMPRISING TITANIUM FOR HYDROTREATMENT OF HYDROCARBON FEEDSTOCKS Technical field

[0001] The present invention relates to the preparation of a mesoporous alumina containing titanium formed from a boehmite gel in which at least one titanium precursor is added in the step of precipitating at least one aluminum salt to form a boehmite gel.

[0002] The titanium-containing alumina according to the invention, due to its advantageous properties, can be used as a catalyst support in all refining processes as well as an adsorbent, in particular for catalytic processes treating hydrocarbon cuts such as the hydrotreatment of vacuum distillates. Prior art

[0003] Patent US10507458 describes the preparation of a hydrotreatment catalyst and an alumina-based catalyst support with the surface covered with different elements such as titanium. Titanium is introduced by excess impregnation onto a boehmite powder which is then shaped by co-mixing with acidified boehmite followed by an extrusion step. The extruded material can be dried and calcined over a temperature range of 250 to 800°C for 1 to 8 hours. The amount of titanium considered in its oxide form is between 0.01 and 2%. The catalyst support has a surface area of ​​between 150 and 280 m2 / g and a pore volume of between 0.4 and 0.9 ml / g.

[0004] Patent US9061265 describes the preparation of a hydrodesulfurization (HDS) catalyst and a catalyst support containing silica, alumina and titanium oxide with a specific structure. This support with specific structure is obtained by a first step of mixing a basic aluminum salt in aqueous solution and a mixed aqueous solution of a titanium acid salt and an aluminum acid salt in the presence of silicate ions, so that the pH is 6.5 to 9.5 to produce a hydrate; a second step is the production of the catalyst support by washing, extrusion, drying and calcination. In the first mixing step an acid source of aluminum and titanium salt is added into a solution containing the basic aluminum and silicon salt. Unlike the present invention, the acid and basic solutions are not added simultaneously in order to have a controlled pH throughout this step.The catalyst is characterized by the fact that the total area of ​​the diffraction peak (101) of anatase and the total area of ​​the diffraction peak (110) of rutile. measured by X-ray diffraction analysis being equal to or less than the % of the diffraction peak area (400) of gamma alumina. The support contains between 1 and 10% of SiO2, between 3 and 40% of TiO2, and between 50 and 96% of A12O3.

[0005] Patents JP4673966 and CN100340338 describe the preparation of a hydrotreatment catalyst and a catalyst support based on alumina and titanium oxide. The amount of titanium supported is 0.5 to 30% by mass relative to the alumina-based oxide. The catalyst support is prepared by the alternate addition of a basic and acidic solution of aluminum salts in a sodium hydroxide solution (pH swing) which leads to the production of an aqueous suspension of boehmite gel. At the end of the precipitation of the boehmite gel a titanium salt solution is added and the whole is filtered, washed, kneaded and extruded. The extrudates obtained are dried and then calcined for 2 hours at 550°C. According to the examples, the obtained catalyst has a porous surface area between 245 and 255 m2 / g and a pore volume between 0.52 and 0.54 cc / g.

[0006] Patent US4465790 describes the preparation of a hydrotreatment catalyst and a catalyst support based on alumina and titanium oxide. The percentage of titanium oxide in the catalyst is between 5 and 40% by mass. The support is prepared by the simultaneous addition to a reactor containing an aqueous solution of gluconic acid and ammonium sulfate of a solution containing an acid salt of aluminum and titanium and a solution containing a basic salt of aluminum. The pH is maintained at 8.5 and the temperature at 54°C. An excess of basic sodium aluminate is added at the end to increase the pH to 10.2. The precipitate obtained is filtered and washed and then spray-dried. The solid obtained is shaped by kneading-extrusion, dried and calcined. Then the active phase containing nickel, molybdenum and phosphorus is introduced by impregnation.

[0007] Patent US9067191 describes the preparation of a hydrodesulfurization (HDS) catalyst and a catalyst support containing silica, alumina and titanium oxide. This support is obtained by a first step of mixing a basic aluminum salt in aqueous solution and a mixed aqueous solution of a titanium acid salt and an aluminum acid salt in the presence of silicate ions, so that the pH is 6.5 to 9.5 to produce a hydrate; a second step is the production of the catalyst support by washing, extrusion, drying and calcination. In the first mixing step an acid source of aluminum and titanium salt is added into a solution containing the basic aluminum and silicon salt. Unlike the present invention, the acid and basic solutions are not added simultaneously in order to have a controlled pH throughout this step.For the catalyst, a specific surface area (SA) greater than 250 m2 / g would tend to decrease the strength of the catalyst and is therefore preferably 250 m2 / g or smaller, more preferably 230 m2 / g or less.

[0008] Patent IN364107 describes the preparation of a hydrotreatment catalyst and a catalyst support containing alumina and titanium oxide. This support is obtained by adding to an aqueous solution of basic aluminum salt also containing an organic salt or a phosphate, an acid source of aluminum and titanium salt. The mixture is maintained at temperature and then filtered and washed with an ammoniacal solution and then treated with an organic acid and aged at a temperature of 95°C. After shaping, calcination and introduction of the active phase, the catalyst obtained has a specific surface area of ​​between 180 and 320 m2 / g, and an average pore diameter measured according to a mercury intrusion method, of between 50 and 110 Å.

[0009] Patent US2022072517 describes the preparation of a hydrotreatment catalyst and a catalyst support containing silica, phosphorus, alumina and optionally titanium oxide. The support is obtained by the gradual addition of an acidic aqueous solution of mineral salts to a basic aqueous solution of mineral salts, the aluminum salt can be acidic or basic. The titanium salt is introduced into the acid solution. The precipitate obtained will be washed, extruded, dried and calcined to obtain the catalyst support. The catalyst support obtained in this patent has a specific surface area of ​​between 280 and 380 m2 / g, an average pore diameter measured according to a mercury intrusion method of between 60 and 100 Å and a pore volume measured according to a mercury intrusion method of between 0.65 and 0.85 ml / g.

[0010] Patent CN111097436 describes the preparation of a hydrotreatment catalyst and a catalyst support based on alumina and containing different elements such as sulfur or titanium. The titanium is introduced into the catalyst support by co-mixing with boehmite acidified by an organic or inorganic acid followed by an extrusion step. Preferably, the source of titanium is titanium oxide. The extruded material can be dried and calcined over a temperature range of 600 to 1000°C, preferably at 800°C for 1 to 10 hours. The amount of titanium considered in its oxide form is between 0.4 and 5%. The catalyst support has in the examples a surface area between 244 and 262 m2 / g, an average pore diameter between 10 and 11 nm and a pore volume between 0.69 and 0.71 ml / g. Additives containing phosphorus and organic molecules can be added to the catalyst preparation.

[0011] Patent CN103372455 describes the preparation of a hydrotreatment catalyst and a catalyst support based on alumina and containing different elements such as titanium. Titanium is introduced into the catalyst support by co-mixing with acidified boehmite followed by an extrusion step. Titanium can also be introduced by impregnation on an alumina type support. The extruded material can be dried and calcined over a temperature range of 350 to 550°C for 2 to 10 hours. The amount of titanium considered in its oxide form is between 1 and 50%. The catalyst support has a surface area between 100 and 350 m2 / g, and a pore volume between 0.4 and 1.2 ml / g. Additives containing phosphorus and organic molecules can be added to the catalyst preparation.

[0012] Patent CN112934209 describes the preparation of a hydrotreatment catalyst and an alumina-based catalyst support with the surface covered with different elements such as titanium. Titanium is introduced in the form of organic titanate solubilized in an organic solvent by excess impregnation on a boehmite powder which is then dried and shaped by kneading followed by an extrusion step. The extruded material can be dried and calcined over a temperature range of 500 to 800°C for 2 to 8 hours. The amount of titanium considered in its oxide form is between 2.5 and 5.5%. The catalyst support has a surface area of ​​between 180 and 250 m2 / g and a pore volume of between 0.79 and 0.95 ml / g. Summary and interest of the invention

[0013] The subject of the present invention is a process for preparing an alumina containing titanium, said process comprising at least the following steps:

[0014] a) at least one or more step(s) of precipitation of a boehmite gel, in an aqueous reaction medium, by the simultaneous addition of at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acid precursor chosen from aluminum sulfate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, in which at least one of the basic or acid precursors comprises aluminum, the relative flow rate of the acid and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.9 and 10.0 and the flow rate of the acid and basic precursor(s) containing aluminum is adjusted so as to obtain a rate of progress of said first step of between 15 and 100% and preferably between 17 and 100%,the rate of progress being defined as being the proportion of boehmite gel formed in A12O3 equivalent during said first precipitation step relative to the total quantity of boehmite gel formed in A12O3 equivalent at the end of the or each of the precipitation steps implemented, said precipitation step operating at a temperature of between 20 and 80°C, and for a duration of between 2 minutes and 30 minutes, ,

[0015] b) optionally one or more heat treatment steps 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,

[0016] c) a step of filtration of the suspension obtained at the end of step a) or even actually at the end of step b) of heat treatment, followed by at least one step of washing the boehmite gel obtained,

[0017] d) a step of drying the boehmite gel obtained at the end of step c) to obtain a powder,

[0018] e) a step of shaping the powder obtained at the end of step d) to obtain the raw material,

[0019] f) a step of drying the raw material obtained in step e) of shaping carried out at a temperature of between 20 and 200°C and for a duration of between 1 hour and 3 weeks to obtain a dried raw material,

[0020] g) a step of heat treatment of the dried raw material obtained at the end of step f) at a temperature of between 500 and 1000°C, and for a duration of between 1 and 12 hours in the presence or absence of a flow of air containing up to 60% by volume of water,

[0021] said method being characterized in that at least one titanium salt is added in at least one or more precipitation step(s) a) and / or optionally in one or more heat treatment step b) in the case where one or more step b) is(are) implemented.

[0022] The process according to the present invention makes it possible to obtain an alumina comprising titanium having textural properties suitable for its use as a catalyst support.

[0023] The method of the present invention may also advantageously comprise at least one step of depositing at least one metal from group VIII, and / or at least one metal from group VIB, and / or at least one dopant chosen from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive on said alumina containing titanium prepared according to the invention.

[0024] Another object of the present invention is a process for hydrotreating feedstocks chosen from hydrocarbon cuts having a distillation range of between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks chosen from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in a mixture, and feedstocks from the reprocessing of biomass / plastics / tires / and household waste, alone or in mixtures, said process using a catalyst comprising at least one metal from group VIII, at least one metal from group VIB, optionally at least one dopant chosen 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 titanium prepared according to the preparation process according to the invention.

[0025] An advantage of the invention is to provide a new process for preparing a titanium-containing alumina, inexpensive compared to conventional alumina preparation processes of the prior art such as, for example, sol-gel type preparation processes. In particular, the process according to the invention does not involve autoclaving treatment and each of the unit steps of the process is economically attractive and already proven on industrial scales.

[0026] Finally, another advantage of the preparation process according to the invention is to allow the production of catalyst supports and associated catalysts exhibiting unmatched performance compared to the catalysts containing or not containing titanium described in the prior art.In particular, the hydrotreatment activity of feedstocks chosen from hydrocarbon cuts having a distillation range of between 250°C and 600°C and renewable feedstocks chosen from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in a mixture, and feedstocks resulting from the reprocessing of biomass / plastics / tires / and household waste, alone or in mixtures, and in particular the hydrotreatment of vacuum distillate cuts of a catalyst comprising the alumina support comprising titanium prepared according to the invention is significantly greater than that of catalysts containing or not containing titanium, prepared according to any method of the prior art known to those skilled in the art.

[0027] In the following text, the groups of chemical elements 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 of columns 8, 9 and 10 according to the new IUP AC classification, and group VIB to the metals of column 6.

[0028] In the remainder of the text, the expressions "between ... and..." and "between .... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this were not the case and the limit values ​​were not included in the range described, such precision will be provided by the present invention.

[0029] In the present description, the expression "greater than..." is understood as strictly greater than, and symbolized by the sign ">", and the expression "less than" as strictly less than, and symbolized by the sign "<".

[0030] Definitions and measurement methods.

[0031] The alumina according to the present invention has a specific pore distribution, where the macropore and mesoporous volumes are measured by mercury intrusion and the micropore volume is measured by nitrogen adsorption.

[0032] By “macropores” is meant pores with an opening greater than 50 nm.

[0033] By “mesopores” is meant pores whose opening is between 2 nm and 50 nm, inclusive.

[0034] By “micropores” we mean pores whose opening is strictly less than 2 nm.

[0035] In the following description of the invention, the pore distribution measured by mercury porosimetry is determined according to the ASTM D4284-83 standard 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 equal to 140° following the recommendations of the work "Techniques de l'ingénieur, traité analyse et caractérisation, P 1050-5, written by Jean Charpin and Bernard Rasneur".

[0036] The value from which the mercury fills all the intergranular voids is set at 0.2 MPa, and it is considered that beyond this the mercury penetrates into the pores of the alumina.

[0037] In order to obtain better precision, the value of the total pore volume corresponds to the value of the total pore volume measured by mercury porosimetry measured on the sample minus 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).

[0038] The macroporous volume is defined as being the cumulative volume of mercury introduced at a pressure between 0.2 MPa and 30 MPa, corresponding to the volume contained in the pores with an apparent diameter greater than 50 nm.

[0039] The mesoporous volume is defined as being the cumulative volume of mercury introduced at a pressure between 30 MPa and 400 MPa, corresponding to the volume contained in the pores with an apparent diameter between 2 and 50 nm.

[0040] The volume of the micropores is measured by nitrogen porosimetry. The quantitative analysis of the 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 work "Adsorption by powders and porous solids. Principles, methodology and applications" written by F. Rouquérol, J. Rouquérol and K. Sing, Academie Press, 1999.

[0041] The median diameter of the mesopores (Dp in nm) is also defined as being a diameter such that all pores smaller than this diameter constitute 50% of the mesoporous volume, measured by mercury porosimetry.

[0042] The pore distribution measured by nitrogen adsorption was determined by the Barrett-Joyner-Halenda (BJH) model. The nitrogen adsorption-desorption isotherm according to the BJH model is described in the periodical "The Journal of American Society", 73, 373, (1951) written by E.P. Barrett, L.G. Joyner and P.P. Halenda. In the following description of the invention, the term "nitrogen adsorption volume" is understood to mean the volume measured for P / Po = 0.99, the pressure for which it is assumed that the nitrogen has filled all the pores.

[0043] In the following description of the invention, the term specific surface area means the surface area BET specific determined by nitrogen adsorption in accordance with ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the periodical "The Journal of American Society", 60, 309, (1938).

[0044] X-ray diffraction on boehmite gels was carried out using the classical powder method using a diffractometer.

[0045] The Scherrer formula is a formula used in X-ray diffraction on powders or polycrystalline samples which relates the width at half-maximum of the diffraction peaks to the size of the crystallites. 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, JI Langford and AJC Wilson. Description of the invention

[0046] Step a) of precipitation

[0047] According to the invention, said preparation process comprises at least one or more step(s) a) of precipitation of a boehmite gel, in an aqueous reaction medium by the simultaneous addition of at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acid precursor chosen from aluminum sulfate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, in which at least one of the basic or acid precursors comprises aluminum, the relative flow rate of the acid and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.9 and 10.0 and the flow rate of the acid and basic precursor(s) containing aluminum is adjusted so as to obtain a progress rate of the first step of between 15 and 100% and preferably between 17 and 100%,the rate of progress being defined as being the proportion of boehmite gel formed in A12O3 equivalent during said precipitation step a) or each of the precipitation steps implemented relative to the total quantity of boehmite gel in A12O3 equivalent formed at the end of the precipitation step(s) and more generally at the end of the steps of preparation of the boehmite gel, said step a) operating at a temperature of between 20 and 80°C, and for a duration of between 2 minutes and 40 minutes.

[0048] Generally speaking, the term "progress rate" of the nth precipitation step means the percentage of boehmite gel formed in A12O3 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.

[0049] Said n-th precipitation step generally makes it possible to obtain a suspension of boehmite gel having an A12O3 concentration of between 20 and 100 g / l, preferably between 20 and 80 g / l, more preferably between 20 and 60 g / l.

[0050] The simultaneous mixing in the aqueous reaction medium of at least one basic precursor and at least one acid precursor requires either that at least the basic precursor or the acid precursor comprises aluminum, or that both the basic and acid precursors comprise aluminum.

[0051] The basic precursors comprising aluminum are sodium aluminate and potassium aluminate. The preferred basic precursor is sodium aluminate.

[0052] The acid precursors comprising aluminum are aluminum sulfate, aluminum chloride and aluminum nitrate. The preferred acid precursor is aluminum sulfate.

[0053] Preferably, the basic and acidic precursor(s) are added in said first precipitation step a) in aqueous solutions.

[0054] Preferably, the aqueous reaction medium is water.

[0055] Preferably, said step a) operates with stirring.

[0056] Preferably, said step a) is carried out in the absence of organic additive and preferably in the absence of gluconic acid.

[0057] Preferably, said step a) is carried out in the absence of a silica source.

[0058] According to the invention, at least one titanium salt is added in at least one or more precipitation step(s) a).

[0059] Said titanium salt is chosen from titanium (IV) oxysulfate, titanium (IV) sulfate, titanium (III) sulfate, titanium trichloride or any other titanium salt.

[0060] Preferably, the reaction medium of step a) is water. The titanium salt is preferably chosen from titanium (IV) oxysulfate and titanium (III) sulfate.

[0061] 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).

[0062] Preferably, the titanium salt is added to the aqueous reaction medium in aqueous solution, simultaneously with said basic aluminum precursor and said acidic aluminum precursor, without having been mixed beforehand with any of said acidic or basic aluminum precursors.

[0063] At least a portion and preferably all of the desired amount of titanium salt is added during said precipitation step(s) a).

[0064] Preferably, the titanium salt is introduced in its entirety in said step(s) a).

[0065] In the case where said method according to the invention comprises several precipitation steps a), the titanium salt can advantageously be added in each of the precipitation steps implemented and preferably the titanium salt is added in the second precipitation step in the case where several precipitation steps are implemented.

[0066] The amount of titanium salt added in said step(s) a) is adjusted so as to that the final alumina obtained comprises a Titanium element content of between 1 and 18% by weight, preferably between 1.3 and 15% and even more preferably between 1.5 and 12%, relative to the total weight of said alumina in A12O3 equivalent.

[0067] The acidic and basic precursors, whether they contain aluminum or not, are mixed simultaneously, preferably in solution, in the aqueous reaction medium which optionally contains the soluble titanium salt, in proportions such that the pH of the resulting suspension is between 8.9 and 10.0.

[0068] In accordance with the invention, it is the relative flow rate of the acidic and basic precursors, whether they contain aluminum or not, which is chosen so as to obtain a pH of the reaction medium between 8.9 and 10.0.

[0069] Preferably, said precipitation step a) is carried out at a pH between 8.9 and 9.8.

[0070] The acid and basic precursors are also mixed in quantities making it possible to obtain a suspension containing the desired quantity of boehmite gel, depending on the final concentration of boehmite gel to be achieved. In particular, said step a) or each of the precipitation steps implemented makes it possible to obtain 15 to 100% by weight of boehmite gel in Al2O3 equivalent relative to the total quantity of boehmite gel formed at the end of the precipitation step(s). In accordance with the invention, it is the flow rate of the acid and basic precursor(s) containing aluminum which is adjusted, depending on the duration of step a), so as to obtain a progress rate of the precipitation step a) of between 15 and 100% and preferably between 17 and 100%.

[0071] In the case where the progress rate obtained at the end of precipitation step a) is less than 100%, at least a second precipitation step is necessary so as to increase the quantity of boehmite gel formed. In the case where a second precipitation step is implemented, the progress rate is defined as being the proportion of boehmite gel formed in A12O3 equivalent during this second precipitation step relative to the total quantity of boehmite gel formed in A12O3 equivalent at the end of all two precipitation steps of the preparation process according to the invention and more generally at the end of the steps for preparing the boehmite gel.

[0072] Thus, depending on the boehmite gel concentration targeted at the end of the precipitation step(s), preferably between 20 and 100 g / l, the quantities of aluminium to be provided by the acid and / or basic precursors are calculated and the flow rate of the precursors is adjusted depending on the concentration of said aluminium precursors added, the quantity of water added to the reaction medium and the rate of progress required for the precipitation step(s).

[0073] In the case where one or more coprecipitation steps are implemented after the first precipitation step, the relative flow rate of the acid and basic precursors is chosen so as to obtain a pH of the reaction medium of said additional precipitation step(s) of between 8.9 and 10.0 and preferably between 8.9 and 9.8.

[0074] The flow rates of the acid and / or basic precursor(s) containing aluminum depend on the size of the reactor used and thus on the quantity of water added to the reaction medium.

[0075] 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.

[0076] In the case where said preparation process according to the invention comprises two precipitation steps, precipitation step a) is advantageously carried out at a temperature lower than the temperature of the second precipitation step.

[0077] 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.

[0078] In the embodiment where several precipitation steps are implemented, preferably, between each precipitation step, a temperature increase can be carried out.

[0079] 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 very preferably between 40 and 65°C.

[0080] In this case, said intermediate temperature rise is preferably implemented for a duration of between 5 and 45 minutes and preferably between 7 and 35 minutes.

[0081] Said intermediate temperature increase is advantageously implemented according to all the heating methods known to those skilled in the art.

[0082] Step b) of heat treatment of the optional suspension

[0083] Said preparation process may optionally comprise one or more steps b) of heat treatment of the suspension obtained at the end of step a), said heat treatment step(s) operating at a temperature of between 70 and 100°C for a duration of between 30 minutes and 5 hours.

[0084] One or more steps b) can advantageously be implemented in the case where a single precipitation step is implemented in the process according to the invention.

[0085] In the case where several precipitation steps a) are implemented, one or more heat treatment steps b) can advantageously be implemented at the end of the last precipitation step a).

[0086] In the case where a step of heat treatment of the suspension obtained at the end of step a) is implemented, at least one preferably soluble titanium salt can possibly be added to the reaction medium during said heat treatment step b).

[0087] Preferably the titanium salt is chosen from titanium (IV) oxysulfate, titanium (IV) sulfate, titanium (III) sulfate, titanium trichloride or any other titanium salt. The titanium salt is preferably chosen from titanium (IV) oxysulfate or titanium (III) sulfate.

[0088] All or part of the desired quantity of titanium salt can advantageously be added in said step(s) b), in the case where at least one step b) is implemented.

[0089] The quantity of titanium salt added in said step(s) b) when it is carried out, is adjusted so that the final alumina obtained comprises a titanium element content of between 1 and 18% by weight, preferably between 1.3 and 15% and even more preferably between 1.5 and 12%, relative to the total weight of said alumina in A12O3 equivalent.

[0090] Preferably, said heat treatment step b) is a ripening step.

[0091] Preferably, said heat treatment step(s) b) operates at a temperature between 70 and 100°C and preferably between 70 and 90°C.

[0092] Preferably, said heat treatment step(s) is / are carried out for a duration of between 30 minutes and 5 hours.

[0093] Said ripening step is advantageously carried out according to all the heating methods known to those skilled in the art.

[0094] Step c) of filtration

[0095] In accordance with the invention, the method according to the invention comprises a step c) of filtration of 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.

[0096] Said filtration step is advantageously followed by at least one water washing step and preferably one to three washing steps, with a quantity of water equal to the quantity of filtered precipitate.

[0097] Step d) of drying

[0098] According to the invention, the boehmite gel obtained at the end of filtration step c) is dried in a drying step d) to obtain a powder.

[0099] Said drying step is advantageously carried out at a temperature between 20 and 200°C, preferably between 40 and 150°C, and for a duration between 1 hour and 3 weeks, preferably between 1 hour and 48 hours, or by atomization.

[0100] In the case where said drying step d) is carried out by atomization, the cake obtained at the end of the heat treatment step, possibly followed by a filtration step, is resuspended. Said suspension is then sprayed into fine droplets, in a vertical cylindrical enclosure in contact with a stream of hot air in order to evaporate the water according to the principle well known to those skilled in the art. The powder obtained is carried by the heat flow to a cyclone or a bag filter which will separate the air from the powder. Preferably, in the case where said drying step d) is implemented by atomization, the atomization 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.

[0101] The boehmite obtained in powder form is advantageously composed of crystallites whose size, obtained by the Scherrer 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.

[0102] The boehmite thus prepared makes it possible to facilitate the step of shaping said gel according to all the methods known to those skilled in the art and in particular by kneading extrusion, by granulation and by the technique known as “oil drop” according to Anglo-Saxon terminology.

[0103] Step e) of shaping

[0104] According to the invention, the powder obtained at the end of drying step d) is shaped in a step e) to obtain a raw material.

[0105] Raw material means the material that has been shaped and has not undergone any heat treatment steps.

[0106] Preferably, said shaping step e) is carried out by extrusion kneading, by pelletizing, by the oil-drop coagulation method, by granulation on a rotating plate or by any other method well known to those skilled in the art.

[0107] Very preferably, said shaping step e) is carried out by extrusion kneading.

[0108] Preferably, said shaping step e) is carried out in the absence of titanium salt.

[0109] In a preferred embodiment, said shaping step e) is carried out by kneading-extrusion, said step e) being carried out with a total acid level, 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 level expressed as a percentage by weight of base relative to the quantity of acid introduced in said step e), of between 0 and 200%.

[0110] Preferably, said step e) is carried out with a total acid level, expressed as a percentage relative to the mass of dried gel introduced in step e), of between 0 and 8%, and very preferably between 0 and 6%, and a neutralization level expressed as a percentage by weight of base relative to the quantity of acid introduced in said step e) of between 0 and 150%, preferably between 0 and 130%, preferably between 0 and 100%, very preferably between 0 and 80% and more preferably between 0 and 60%.

[0111] 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.

[0112] Preferably the base used in step e) is chosen from inorganic bases chosen from sodium hydroxide, potassium hydroxide, and ammonia, and organic bases in solution chosen from amines and quaternary ammonium compounds. Preferably the organic bases in solution are chosen from alkylethanol amines and ethoxylated alkylamines. The organic bases are preferably used in solution in water.

[0113] Very preferably, said base is ammonia and preferably ammonia in aqueous solution (NH40H+ H2O).

[0114] Step f) of drying

[0115] In accordance with the invention, the raw material obtained at the end of shaping step e) is dried in a drying step f) carried out at a temperature of 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, to obtain a dried raw material.

[0116] Step g) of heat treatment

[0117] In accordance with the invention, the dried raw material obtained at the end of drying step f) then undergoes a heat treatment step g) at a temperature of between 500 and 1000°C, for a duration of between 1 and 12 h, in the presence or absence of an air flow containing up to 60% by volume of water.

[0118] Preferably, said heat treatment step g) operates at a temperature between 520 and 850°C, preferably between 520 and 800°C and even more preferably between 530 and 750°C.

[0119] Preferably, said heat treatment step g) operates for a duration of between 1 hour and 12 hours, preferably between 1 hour 30 minutes and 10 hours and even more preferably between 2 hours and 8 hours.

[0120] Said heat treatment step g) allows the transition of boehmite to the final alumina, and allows the final porous texture of the alumina prepared according to the invention and which contains Titanium to be adjusted.

[0121] The content of titanium element in the material and preferably the alumina obtained at the end of step g) is preferably between 1 and 18%, preferably between 1.3 and 15% and even more preferably between 1.5 and 12%, relative to the total weight of said alumina in A12O3 equivalent.

[0122] The preparation process according to the invention makes it possible to obtain a mesoporous alumina containing titanium and having a controlled mesoporosity with good thermal and chemical stability, having a centered, uniform and controlled mesopore size distribution, and a specific surface area and a calibrated pore volume and in particular mesoporous volume.

[0123] The process according to the present invention makes it possible to obtain an alumina comprising titanium having textural properties suitable for its use as a catalyst support.

[0124] Preferably, said alumina comprises a titanium element content of between 1 and 18%, preferably between 1.3 and 15% and even more preferably between 1.5 and 12%, relative to the total weight of said alumina in A12O3 equivalent.

[0125] Said mesoporous alumina containing titanium prepared according to the process of the invention is preferably free of micropores. The absence of micropores is measured and verified by nitrogen adsorption.

[0126] The mesoporous alumina containing titanium prepared according to the process of the invention and obtained at the end of heat treatment step g) advantageously has a BET specific surface area of ​​between 50 and 450 m2 / g, preferably between 100 and 400 m2 / g, more preferably between 200 and 400 m2 / g, and very preferably between 220 and 380 m2 / g. and a mesoporous volume greater than or equal to 0.5 ml / g, preferably between 0.55 and 0.85 ml / g, very preferably between 0.60 and 0.80 ml / g and even more preferably between 0.65 and 0.78 ml / g.

[0127] Preferably, the total pore volume of said titanium-containing alumina measured by mercury porosimetry is between 0.6 and 0.9 ml / g.

[0128] Preferably, the percentage of volume included in the pores of size between 2 and 50 nm relative to the total pore volume of said alumina containing titanium measured by mercury porosimetry, is greater than 90% and preferably greater than 95%.

[0129] The median diameter of the mesopores measured by mercury porosimetry of said titanium-containing alumina, determined by volume, is advantageously 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.

[0130] Preferably, the percentage of the mesoporous volume of the pores having a diameter between 8 and 20 nm measured by mercury porosimetry is between 60 and 100%, preferably, it is between 65 and 100%.

[0131] Preferably, the alumina according to the invention is a non-mesostructured alumina.

[0132] Said mesoporous alumina containing titanium has a sulfur content between 0.001% and 0.4% by weight and a sodium content between 0.001% and 0.04% by weight, the weight percentages being expressed relative to the total mass of boehmite gel in its A12O3 form.

[0133] Preferably, the titanium-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, the specific shape of which may result from a crushing step.

[0134] Preferably, said titanium-containing alumina prepared according to the invention is used as a catalyst support. The shape taken by the support comprising said titanium-containing alumina is that of extrudates whose diameter is between 0.8 and 3 mm, preferably between 1.2 and 2.6 mm. The geometry of the extrudates can be cylindrical, trilobal, quadrilobal or any other advantageous shape depending on the desired application.

[0135] A catalyst can advantageously be prepared from the titanium-containing alumina prepared according to the invention and used as a support for said catalyst.

[0136] 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 those skilled in the art.

[0137] The method according to the invention may advantageously comprise a step h) of depositing on said titanium-containing alumina resulting from step g) at least one metal from group VIII and / or at least one metal from group VIB of the periodic table of elements and / or a doping element chosen from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive. In the case where an organic additive is deposited, its deposition is followed by a drying step without calcination. In the case where no organic additive has been deposited, the deposition of the metals is followed by a drying step and optionally a calcination step.

[0138] The metal(s) from group VIII and / or at least one metal from group VIB may advantageously be introduced in one or more stages and preferably by dry or excess impregnation.

[0139] In a preferred embodiment, at least one metal from group VIII, at least one metal from group VIB, at least one dopant chosen from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive are deposited on said support.

[0140] The group VIB metal present in the active phase of the catalyst is preferably chosen from molybdenum and tungsten. The group VIII metal present in the active phase of the catalyst is preferably chosen from cobalt, nickel and the mixture of these two elements. The active phase of the catalyst is preferably chosen from the group formed by the combination of the elements 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.

[0141] The content of group VIII metal in the catalyst is less than 20% by weight, preferably between 0.03 and 15% by weight, very 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.

[0142] The content of group VIB metal in the catalyst is between 1 and 50% by weight, preferably between 5 and 40% by weight, and more preferably between 10 and 35% by weight and even more preferably between 15 and 30% by weight expressed as group VIB metal oxide relative to the total weight of the catalyst.

[0143] The molar ratio of group VIII metal to group VIB metal of the catalyst is generally less than 1, preferably between 0.01 and 0.75, and very preferably between 0.10 and 0.60 and even more preferably between 0.20 and 0.50.

[0144] Optionally, the catalyst may also have a phosphorus content generally less than 15% by weight, preferably between 0.1 and 10% by weight, very 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.

[0145] Furthermore, in the case where the catalyst comprises phosphorus, the phosphorus / (group VIB metal) molar ratio is generally between 0.02 and 1, preferably between 0.04 and 0.8, and very preferably between 0.1 and 0.75.

[0146] The catalyst may also further comprise at least one organic compound containing oxygen and / or nitrogen and / or sulfur before sulfurization. Such additives are known to those skilled in the art. Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or else compounds including a furan cycle or else sugars.

[0147] The content of organic compound(s) containing oxygen and / or nitrogen and / or sulfur on 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 one of the catalyst preparation steps is in an amount corresponding to:

[0148] - at a compound molar ratio added per metal(s) of group VIB present in the regenerated catalyst 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 very preferably between 0.02 and 0.08 mol / mol,

[0149] - and at a compound molar ratio added per group VIII metal(s) present in the regenerated catalyst between 0.02 and 6.0 mol / mol, preferably between 0.03 and 4.0 mol / mol, more preferably between 0.04 and 3.0 mol / mol, and very preferably between 0.05 and 0.4 mol / mol.

[0150] 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.

[0151] The oxygen-containing organic compound may be one or more selected from a carboxylic acid, an alcohol, an aldehyde, or an ester. For example, the oxygen-containing organic compound may be one or more selected from the group consisting of ethylene glycol, glycerol, polyethylene glycol (with a molecular weight of 200 to 1500), 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 an organic carboxylic 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,

[0152] According to a variant of the invention, when an organic compound is present, the fresh catalyst has not undergone calcination during its preparation, that is to say that 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.

[0153] Another subject of the present invention is a process for hydrotreating hydrocarbon cuts using a catalyst containing an alumina comprising titanium, said alumina being prepared according to the preparation process according to the invention.

[0154] In particular, another object of the present invention is a process for hydrotreating feedstocks chosen from hydrocarbon cuts having a distillation range of between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks chosen from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in a mixture, and feedstocks from the reprocessing of biomass / plastics / tires / and household waste, alone or in mixtures, said process using a catalyst comprising at least one metal from group VIII, at least one metal from group VIB, optionally at least one dopant chosen 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 titanium prepared according to the preparation method according to the invention.

[0155] Before its use in a process for hydrotreating hydrocarbon fractions, the catalyst is generally subjected to sulfurization in order to obtain the metals in their sulfurized or partially sulfurized forms as described below. This activation or sulfurization step is carried out by methods well known to those skilled in the art, and advantageously under a sulfide-reducing atmosphere in the presence of hydrogen and hydrogen sulfide.

[0156] Said catalyst is advantageously sulfurized ex situ or in situ. The sulfurizing agents are H2S gas, elemental sulfur, CS2, mercaptans, sulfides and / or polysulfides, hydrocarbon cuts with a boiling point below 400°C containing sulfur compounds or any other compound containing sulfur used for the activation of hydrocarbon feedstocks in order to sulfurize the catalyst. Said sulfur-containing compounds are advantageously chosen 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-butanethiol) and polysulfide compounds of the tert-onylpolysulfide type. The catalyst can also be sulfurized by the sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfurized in situ in the presence of a sulfurizing agent and a hydrocarbon feedstock.Very preferably, the catalyst is sulfurized in situ in the presence of a hydrocarbon feedstock with added dimethyl disulfide.

[0157] Use of a catalyst prepared from a support prepared according to the invention

[0158] Preferably, the so-called heavy hydrocarbon feedstocks are chosen from the charges having a weighted average temperature (WAT) greater than 380°C. WAT is defined from the temperature at which 5%, 50% and 70% of the charge volume distill according to 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 charge is greater than 380°C and preferably less than 600°C, and more preferably less than 580°C.

[0159] According to the invention, the treated hydrocarbon feedstock preferably has a distillation range of between 250°C and 600°C, preferably between 300 and 580°C.

[0160] Said hydrocarbon feedstock is advantageously chosen from LCO or HCO (Light Cycle Oil or Heavy Cycle Oil according to the 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 oil or from conversion units such as catalytic cracking, coker or visbreaking, feedstocks from from aromatics extraction units, lubricating oil bases or from solvent dewaxing of lubricating oil bases, distillates from fixed bed or ebullated bed desulfurization or hydroconversion processes of atmospheric residues and / or vacuum residues and / or deasphalted oils, or the feedstock may be a deasphalted oil.

[0161] Preferably, said hydrocarbon feedstock is a vacuum distillate.

[0162] Any hydrocarbon feedstock containing sulfur and nitrogen compounds that inhibit hydrotreatment, and a TMP similar to that of a vacuum distillate cut may be concerned by the process which is the subject of the present invention. The hydrocarbon feedstock may be of any chemical nature, that is to say have any distribution between the different chemical families, in particular paraffins, olefins, naphthenes and aromatics.

[0163] Said hydrocarbon feedstock 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, for example, pyrroles, indoles, carbazoles and their derivatives. It is in particular the basic nitrogenous molecules which inhibit hydrotreatment catalysts, and in particular additive catalysts.

[0164] The nitrogen content is greater than or equal to 250 ppm, preferably it is between 400 and 10000 ppm by weight, more preferably between 700 and 4000 ppm by weight and even more preferably between 1000 and 4000 ppm. The basic nitrogen content has at least a quarter of the overall nitrogen content (nitrogen). The basic nitrogen content is generally greater than or equal to 60 ppm, more preferably between 175 and 1000 ppm by weight and even more preferably between 250 and 1000 ppm.

[0165] 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.

[0166] Said hydrocarbon feedstock may optionally advantageously contain metals, in particular nickel and vanadium. The cumulative nickel and vanadium content of said hydrocarbon feedstock, treated according to the hydrocracking process according to the invention, is preferably less than 1 ppm by weight.

[0167] 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.

[0168] The treated filler generally contains resins, preferably the resin content is greater than 1% by weight, more preferably greater than 5% by weight. The measurement of the resin content is carried out according to the ASTM D 2007-11 standard.

[0169] According to the invention, said charge treated in the hydrotreatment process is chosen among the renewable feedstocks chosen from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in a mixture, and feedstocks from the reprocessing of biomass / plastics / tires / and household waste, alone or in a mixture.

[0170] Said charge treated according to the hydrotreatment process of the invention may also be a mixture of said charges previously cited.

[0171] The catalyst prepared from the titanium-containing alumina support according to the invention can then be used in one, two or more reactors. It is generally used for implementation in a fixed bed.

[0172] The operating conditions used for the operation, preferably in a fixed bed, of the catalyst prepared from the alumina support containing titanium according to the invention correspond to those generally used for a hydrotreatment 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 flow rate (defined as the ratio of the volumetric flow rate of feedstock to the volume of catalyst per hour) is advantageously between 0.1 and 20 h 1 and preferably between 0.2 and 5 h 1, and the hydrogen / feedstock ratio expressed in volume of hydrogen, measured under normal temperature and pressure conditions, per volume of liquid feedstock is advantageously between 50 1 / 1 and 2000 1 / 1.

[0173] The invention is illustrated by the following examples which are in no way limiting. Examples:

[0174] Example 1 in accordance with the invention (addition of 4.9% Titanium to obtain a final alumina containing 3.25% titanium in the second precipitation stage):

[0175] The preparation of an alumina is carried out according to a preparation method in accordance with the invention with the addition of the titanium salt in the second coprecipitation step. Stirring is 350 rpm throughout the synthesis.

[0176] The synthesis of the boehmite gel is carried out according to a preparation method in accordance with the invention in a 5 L reactor in two precipitation stages.

[0177] The final concentration of boehmite gel considered in the targeted A12O3 form is 43 g / l. The quantity of water added to the reactor before the first co-precipitation is 1527 mL of water.

[0178] A first step of co-precipitation in water, of aluminum sulfate A12(SO4) and sodium aluminate NaAlOO added simultaneously 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: A12(SO4)= 102 g / 1 in A12O3 and NaAlOO at 155 g / 1 in A12O3.

[0179] A solution of aluminum sulfate A12(SO4)3 is continuously added to the reactor containing the water for 8 minutes at a flow rate of 12.5 ml / min simultaneously with a solution of sodium aluminate NaAlOO at a flow rate of 15 ml / min so as to adjust the pH to a value of 9.4. The temperature of the reaction medium is maintained at 40°C.

[0180] A suspension containing a precipitate of boehmite gel is obtained.

[0181] The progress rate of the first precipitation stage is 17.5%.

[0182] The suspension obtained is then subjected to a temperature increase from 40 to 60°C in 30 minutes.

[0183] A second step of co-precipitation of the suspension obtained is then carried out by simultaneous addition of aluminum sulfate A12(SO4)3 at a concentration of 102 g / L in A12O3, sodium aluminate NaAlOO at a concentration of 155 g / L in A12O3 and a solution of titanium (III) sulfate at a concentration of 8.52 g / L in Ti. A solution of aluminum sulfate A12(SO4)3 is therefore continuously added to the heated suspension obtained at the end of the first precipitation step for 30 minutes at a flow rate of 10.3 ml / min simultaneously with a solution of titanium (III) sulfate at a flow rate of 39 ml / min and with a solution of sodium aluminate NaAlOO at a flow rate of 13.5 ml / min so as to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second stage is maintained at 60°C.

[0184] These flow rates of acidic and basic precursors containing aluminum make it possible to obtain at the end of the second precipitation stage a progress rate of 82.5%, the cumulative progress rate of the first and second precipitation stages being equal to 100%.

[0185] A suspension containing a precipitate of boehmite gel containing titanium is obtained.

[0186] The suspension obtained is then filtered by water displacement on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 5 L of distilled water.

[0187] The characteristics of the boehmite gel thus obtained are summarized in Table 1.

[0188] Table 1: characteristics of the boehmite gel obtained according to Example 1.

[0189] [Tables 1] Example 1: Size (020) (nm) 2.70 Size (120) (nm) 3.90

[0190] The titanium-containing boehmite gel obtained according to Example 1 was dried in a ventilated study at 120°C for 16 hours.

[0191] The dried boehmite gel is then introduced into a Brabender-type mixer. Water acidified with nitric acid to a total acid content of 4%, expressed as weight relative to the mass of dried powder considered in the form A12O3 introduced into the mixer, is added over 5 minutes, during mixing at 20 rpm. The acid mixing is continued for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer, at a neutralization rate of 100%, expressed as the weight of ammonia relative to the quantity of nitric acid introduced into the mixer for the acidification step. The mixing is continued for 3 minutes.

[0192] The paste obtained is then extruded through a 2 mm trilobed die. The extrudates obtained are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under an air flow containing no water. The alumina obtained exhibits the characteristic peaks of a gamma alumina in X-ray diffraction. The textural characteristics of the formed gamma alumina containing titanium are reported in Table 2:

[0193] Table 2: characteristics of alumina A containing titanium obtained according to example 1.

[0194] [Tables2] Example 1 SBET(m2 / g) 292 VPT (Hg) (ml / g) 0.66 Dp (Hg) (nm) 9.9% VP(Hg) between 8 and 20nm 70 Sodium Na (%) 0.0049 Sulfur S (%) 0.0860 Titanium Ti (%) 3.25

[0195] Example 2 in accordance with the invention (addition of 3% Titanium to obtain a final alumina containing 2% titanium in the second precipitation stage):

[0196] The preparation of an alumina is carried out according to a preparation method in accordance with the invention with the addition of the titanium salt in the second coprecipitation step. Stirring is 350 rpm throughout the synthesis.

[0197] The synthesis of the boehmite gel is carried out according to a preparation method in accordance with the invention in a 5 L reactor in two precipitation stages.

[0198] The final concentration of boehmite gel considered in the targeted A12O3 form is 43 g / l. The quantity of water added to the reactor before the first co-precipitation is 1527 mL of water.

[0199] A first step of co-precipitation in water, of aluminum sulfate A12(SO4 ) and sodium aluminate NaAlOO added simultaneously is carried out at 40°C and pH=9.4 for a period of 8 minutes. The concentrations of the aluminum precursors used are as follows: A12(SO4)= 102 g / 1 in A12O3 and NaAlOO at 155 g / 1 in A12O3.

[0200] A solution of aluminum sulfate A12(SO4)3 is continuously added to the reactor containing the water for 8 minutes at a flow rate of 12.5 ml / min simultaneously with a solution of sodium aluminate NaAlOO at a flow rate of 15 ml / min so as to adjust the pH to a value of 9.4. The temperature of the reaction medium is maintained at 40°C.

[0201] A suspension containing a precipitate of boehmite gel is obtained.

[0202] The progress rate of the first precipitation stage is 17.5%.

[0203] The suspension obtained is then subjected to a temperature increase from 40 to 60°C in 30 minutes.

[0204] A second step of co-precipitation of the suspension obtained is then carried out by simultaneous addition of aluminum sulfate A12(SO4)3 at a concentration of 102 g / L in A12O3, sodium aluminate NaAlOO at a concentration of 155 g / L in A12O3 and a solution of titanium (III) sulfate at a concentration of 8.52 g / L in Ti. A solution of aluminum sulfate A12(SO4)3 is therefore continuously added to the heated suspension obtained at the end of the first precipitation step for 30 minutes at a flow rate of 10.3 ml / min simultaneously with a solution of titanium (III) sulfate at a flow rate of 23.9 ml / min and with a solution of sodium aluminate NaAlOO at a flow rate of 13.5 ml / min so as to adjust the pH to a value of 9.7. The temperature of the reaction medium in the second stage is maintained at 60°C.

[0205] These flow rates of acid and basic precursors containing aluminum make it possible to obtain at the end of the second precipitation stage a progress rate of 82.5%, the cumulative progress rate of the first and second precipitation stages being equal to 100%.

[0206] A suspension containing a precipitate of boehmite gel containing titanium is obtained.

[0207] The suspension obtained is then filtered by water displacement on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 5 L of distilled water.

[0208] The characteristics of the boehmite gel thus obtained are summarized in Table 3.

[0209] Table 3: characteristics of the boehmite gel obtained according to Example 2.

[0210] [Tables3] Example 2: Size (020) (nm) 2.62 Size (120) (nm) 3.84

[0211] The titanium-containing boehmite gel obtained according to Example 2 was dried in a ventilated study at 120°C for 16 hours.

[0212] The dried boehmite gel is then introduced into a Brabender type mixer. Water acidified with nitric acid at a total acid level of 4%, expressed by weight relative to the mass of dried powder considered in the form A12O3 introduced into the mixer, is added over 5 minutes, during mixing at 20 rpm. The acid mixing is continued for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer, at a neutralization level of 100%, expressed by weight of ammonia relative to the quantity of nitric acid introduced into the mixer for the acidification step. The mixing is continued for 3 minutes.

[0213] The paste obtained is then extruded through a 2 mm trilobed die. The extrudates obtained are dried at 100°C for 16 hours and then calcined for 4 hours at 540°C under an air flow containing no water. The alumina obtained exhibits the characteristic peaks of a gamma alumina in X-ray diffraction. The textural characteristics of the formed gamma alumina containing titanium are reported in Table 4:

[0214] Table 4: characteristics of alumina B containing titanium obtained according to example 2.

[0215] [Tables4] Example 2 SBET(m2 / g) 298 VPT (Hg) (ml / g) 0.67 Dp (Hg) (nm) 9.9% VP(Hg) between 8 and 20nm 72 Sodium Na (%) 0.0046 Sulfur S (%) 0.0840 Titanium Ti (%) 2.0

[0216] Example 3 not in accordance with the invention (addition of Ti (3.25%) by impregnation on alumina

[0217] The preparation of an alumina is carried out according to a preparation process not in accordance with the invention in which the addition of all the soluble titanium salt is carried out after the heat treatment step by calcination and without any addition of titanium salt in the precipitation or shaping steps. Stirring is 350 rpm throughout the synthesis.

[0218] The synthesis of the boehmite gel is carried out according to a preparation method of the prior art in a 5 L reactor and for a final suspension volume of 3.5 L in two precipitation stages.

[0219] The final concentration of boehmite gel considered in the targeted form of A12O3 is 36g / l. The quantity of water added to the reactor before the first co-precipitation is 1160 mL of water.

[0220] A first step of co-precipitation in water, aluminum sulfate A12(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: A12(SO4)= 102g / l in A12O3 and NaAlOO at 155g / l in A12O3.

[0221] A solution of aluminum sulfate A12(SO4) is continuously added to the reactor containing the water for 8 minutes at a flow rate of 13.8 ml / min simultaneously with a solution of sodium aluminate NaAlOO at a flow rate of 17.5 ml / min so as to adjust the pH to a value of 9.4. The temperature of the reaction medium is maintained at 40°C.

[0222] A suspension containing a precipitate of boehmite gel is obtained.

[0223] The progress rate of the first precipitation stage is 25%.

[0224] The suspension obtained is then subjected to a temperature increase from 40 to 60°C in 30 minutes.

[0225] A second step of co-precipitation of the suspension obtained is then carried out by adding aluminum sulfate A12(SO4) at a concentration of 102g / l in A12O3 and sodium aluminate NaAlOO at a concentration of 155g / L in A12O3. A solution of aluminum sulfate A12(SO4) is therefore continuously added to the heated suspension obtained at the end of the first precipitation step for 30 minutes at a flow rate of 10.3 ml / min simultaneously with a solution of sodium aluminate NaAlOO at a flow rate of 14.2 ml / min so as 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.

[0226] These flow rates of acidic and basic precursors containing aluminum make it possible to obtain at the end of the second precipitation stage a progress rate of 75%, the cumulative progress rate of the first and second precipitation stages being equal to 100%.

[0227] The suspension obtained is then filtered by water displacement on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 5 L of distilled water.

[0228] The characteristics of the boehmite gel thus obtained are summarized in Table 5.

[0229] Table 5: characteristics of the boehmite gel obtained according to Example 3.

[0230] [Tables5] Example 3: Size (020) (nm) 3.21 Size (120) (nm) 3.71

[0231] The boehmite gel obtained according to Example 3 was dried in a ventilated study at 120°C for 16 hours.

[0232] The dried boehmite gel is then introduced into a Brabender type mixer. Water acidified with nitric acid at a total acid level of 4%, expressed by weight relative to the mass of dried gel considered in the form A12O3 introduced into the mixer, is added over 5 minutes, during mixing at 20 rpm. The acid mixing is continued for 15 minutes. A neutralization step is then carried out by adding an ammonia solution to the mixer, at a neutralization level of 40%, expressed by weight of ammonia relative to the quantity of nitric acid introduced into the mixer for the acidification step. The mixing is continued for 3 minutes.

[0233] The paste obtained is then extruded through a 2 mm trilobed die. The extrudates obtained are dried at 100°C for 16 hours and then calcined for 4 hours at 600°C under a flow of dry air. The alumina C obtained exhibits the characteristic peaks of a gamma alumina in X-ray diffraction. The textural characteristics of the gamma alumina formed are reported in Table 6:

[0234] Table 6: characteristics of alumina C obtained according to example 3.

[0235] [Tableauxô] Example 3 SBET(m2 / g) 250 VPT (Hg) (ml / g) 0.60% VP(Hg) between 8 and 20nm 60 Dp (Hg) (nm) 8.9 Sodium Na (%) 0.068 Sulfur S (%) 0.0757

[0236] 100 g of alumina C extrudates obtained according to example 3 are dry impregnated with 60 mL of aqueous solution containing 13g of titanium (III) sulfate. After impregnation, the extrudates are kept at room temperature for 3 hours and then they are dried at 100°C for 16 hours and then calcined for 4 h at 540°C to produce alumina D. Chemical analysis of these extrudates indicates a mass percentage of 3.23% titanium relative to the mass of alumina in its A12O3 form.

[0237] Example 4:

[0238] Supports A to D were dry impregnated with an aqueous solution based on nickel and molybdenum, aiming for molybdenum and nickel contents of 29% by weight and 4.7% by weight respectively, expressed in their oxide form, which corresponds to a theoretical molar ratio of 0.32. After a 6-hour maturation step in a closed vessel, the extrudates were dried at 160°C for 1 hour before being again dry impregnated with an aqueous solution containing triethylene glycol (TEG) so that the TEG / Mo molar ratio was 0.8. A final drying was then applied to the extrudates for one hour in air at 90°C.

[0239] The catalysts thus obtained were then evaluated in hydrodenitrogenation of a vacuum distillate whose TMP is 474°CC (T5% = 389°C, T50% = 468°C, T70% = 498°C). The characteristics of the feed are as follows: sulfur 2.6% by weight, nitrogen 1350 ppm, basic nitrogen 392 ppm, resins 9.1% by weight.

[0240] The test is carried out in an isothermal fixed-bed pilot reactor with fluids circulating from bottom to top.

[0241] After in situ sulfurization at 350°C in the pressure unit using the vacuum distillate from the test to which 2% by weight of dimethyl disulfide was added, the hydrotreatment test was carried out under the following operating conditions: a total pressure of 160 bar (16 Mpa), a WH of 1.5 h-1, an H2 / feed ratio of 1000 1 / h and a temperature of 370°C.

[0242] The following table shows the percentage of relative HDN carried out in the reactor. The percentage HDN is calculated as follows: HDN (%) = (Noutput - Ninput) / Ninput. The relative %HDN is reduced to a base of 100 corresponding to the reference case without Titanium.

[0243] [Tables?] Alumina support containing Ti A Complies with the invention B Complies with the invention C Not in accordance with the invention D Not in accordance with the invention %Ti 3.3 2.0 ** 3.2 Method of introducing Titanium Precipitation of boehmite (2nd stage) Precipitation of boehmite (2nd stage) so impregnation pH precipitation 1 9.4 9.4 9.4 9.4 pH precipitation 2 9.7 9.7 9.7 9.7 VPT Hg (ml / g) 0.66 0.67 0.60 0.58 Vmeso (ml / g) 0.66 0.66 0.60 0.58 %VP between 8 and 20nm 70 72 60 56 Median Dp (nm) 9.9 9.9 8.9 8.6 %NiO 4.8 4.7 4.8 4.6 %MoO3 29.1 29.1 29.2 29.3 %HDN 107 105 100 98

[0244] The examples below make it possible to highlight the advantage of introducing a small amount of Titanium during the preparation of an alumina support according to the process of the invention and in particular during the second coprecipitation step. Indeed, it is first noted that when Titanium is introduced during the precipitation and in particular the second coprecipitation step (supports A or B with two different titanium contents), specific textural characteristics are obtained. Indeed, for similar preparation conditions, but without added Titanium (support C), the textural characteristics are very different, in particular support C has a pore volume and a median diameter lower than those of supports A and B.In particular, the addition of Titanium according to the process of the invention makes it possible to maximize / optimize the useful porosity between 8 and 20 nm, while retaining high specific surfaces (%VP between 8 and 20 nm of support C = 60% while that of supports A and B is equal to 70 and 72% respectively).

[0245] Furthermore, the examples provided highlight the interest of these textural distributions combined with the presence of Titanium since the performances in hydrodenitrogenation of vacuum distillate feedstocks, catalysts prepared in an identical manner from the various supports are significantly higher with supports A and B prepared according to the invention than with non-compliant support C which does not contain Titanium or the desired textural characteristics. In addition, the catalyst prepared with support D which, following impregnation, also has Titanium, does not prove to be more efficient than that prepared with the support without titanium C, on the contrary, highlighting the interest of the preparation process according to the invention.

Claims

Claims

1. A process for preparing a titanium-containing alumina, said process comprising at least the following steps: a) at least one or more step(s) of precipitation of a boehmite gel, in an aqueous reaction medium, by the simultaneous addition of at least one basic precursor chosen from sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acid precursor chosen 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 acid and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.9 and 10,0 and the flow rate of the acidic and basic precursor(s) containing aluminum is adjusted so as to obtain a progress rate of said first step of between 15 and 100%, the progress rate being defined as being the proportion of boehmite gel formed in A12O3 equivalent during said first precipitation step relative to the total quantity of boehmite gel formed in Al2 O3 equivalent at the end of the or each of the precipitation steps implemented, said precipitation step operating at a temperature of between 20 and 80°C, and for a duration of between 2 minutes and 40 minutes, b) optionally one or more heat treatment step(s) of the suspension obtained at the end of step a) at a temperature of between 70 and 100°C for a duration of between 30 minutes and 5 hours, c) a filtration step of 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 boehmite gel obtained, d) a step of drying the boehmite gel obtained at the end of step c) to obtain a powder, e) a step of shaping the powder obtained at the end of step d) to obtain the raw material, f) a step of drying the raw material obtained in step e) of shaping carried out at a temperature of between 20 and 200°C and for a duration of between 1 hour and 3 weeks to obtain a, dried raw material, g) a step of heat treatment of the dried raw material obtained at the end of step f) at a temperature between 500 and 1000°C, in the presence or absence of an air flow containing up to 60% by volume of water, said process being characterized in that at least one titanium salt is added in at least one or more step(s) a) of precipitation and / or optionally in one or more step 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 titanium salt is soluble in said reaction medium of said step a) and is chosen from titanium (IV) oxysulfate, titanium (III) sulfate, titanium (IV) sulfate and titanium trichloride and preferably titanium (IV) oxysulfate and titanium (III) sulfate.

3. Method according to claim 1 wherein the titanium salt is added in each of the precipitation steps a) carried out and preferably the titanium salt is added in the second precipitation step, in the case where said method comprises several precipitation steps a).

4. A method according to any preceding claim wherein the titanium salt is added to the aqueous reaction medium in aqueous solution, simultaneously with said basic aluminum precursor and said acidic aluminum precursor, without having been previously mixed with any of said acidic or basic aluminum precursors.

5. Method according to one of the preceding claims in which said drying step d) is carried out at a temperature between 20 and 200°C, preferably between 40 and 150°C and for a duration between 1 hour and 3 weeks and preferably between 1 hour and 48 hours or by atomization.

6. Method according to one of the preceding claims in which said shaping step e) is carried out by extrusion kneading.

7. Method according to one of the preceding claims in which the mesoporous alumina containing titanium obtained at the end of step g) of heat treatment has a BET specific surface area of ​​between 50 and 450 m2 / g, a total pore volume measured by mercury porosimetry of between 0.6 and 0.9 ml / g, a percentage of volume included in the pores of size of between 2 and 50 nm relative to the total pore volume measured by mercury porosimetry, greater than 90%, a median diameter of the mesopores measured by mercury porosimetry mercury, determined in volume between 7 and 13.5 nm, and a percentage of the mesoporous volume of pores having a diameter between 8 and 20 nm measured by mercury porosimetry between 60 and 100%.

8. Method according to one of the preceding claims in which a step h) of depositing 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 doping element chosen from boron, phosphorus and silicon and preferably phosphorus and optionally at least one organic additive, on said alumina containing titanium resulting from step g) is carried out.

9. Process for hydrotreating feedstocks chosen from hydrocarbon cuts having a distillation range of between 250°C and 600°C, preferably vacuum distillates, and renewable feedstocks chosen from vegetable oils, algal oils, cooking oils, animal fats, fresh or used, alone or in a mixture, and feedstocks from the reprocessing of biomass / plastics / tires / and household waste, alone or in mixtures, said process using a catalyst comprising at least one metal from group VIII, at least one metal from group VIB, optionally at least one dopant chosen 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 titanium prepared according to one of claims 1 to 8.

10. A process according to claim 9 wherein the temperature of the hydrotreatment 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, the hourly volumetric flow rate (defined as the ratio of the volume flow rate of feedstock to the volume of catalyst per hour) is between 0.1 and 20 h-1 and preferably between 0.2 and 5 h-1, and the hydrogen / feedstock ratio expressed as the volume of hydrogen, measured under standard temperature and pressure conditions, per volume of liquid feedstock is between 50 1 / 1 and 2000 1 / 1.