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    • 专利摘要:
    An amorphous mesoporous alumina with connectivity (Z) greater than 2.7 is described. The present invention also relates to the process for preparing said alumina comprising at least one step of precipitating at least one aluminum salt, at least one step of heating the suspension obtained, a heat treatment step to form the gel of alumina, a mild or spray drying step, a shaping step of the obtained powder and a final heat treatment step to obtain the alumina.
    公开号:FR3022238A1
    申请号:FR1455423
    申请日:2014-06-13
    公开日:2015-12-18
    发明作者:Malika Boualleg；Celine Bouvry
    申请人:IFP Energies Nouvelles IFPEN；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD The present invention relates to the preparation of an amorphous mesoporous alumina shaped from an alumina gel having a high dispersibility, said alumina gel being obtained by precipitation of at least one salt. In particular, the present invention relates to an amorphous mesoporous alumina having a very high connectivity with respect to the aluminas of the prior art.The present invention also relates to the process for the preparation of said alumina by shaping an alumina gel, said alumina gel being prepared according to a method of preparation by specific precipitation, making it possible to obtain at least 40% by weight of alumina with respect to the total amount of alumina formed in the resulting from the gel preparation process, the first precipitation step, the amount of alumina formed at the end of the first precipitation step can even reach The alumina according to the invention, because of its interesting properties, in particular in terms of connectivity, can be used as a catalyst support in all refining processes as well as as adsorbent. PRIOR ART US Pat. No. 4,676,928 describes a process for producing a water-dispersible alumina comprising a step of forming an aqueous alumina dispersion, a step of adding an acid to produce an acidic dispersion. having a pH of between 5 and 9, a maturation step at an elevated temperature above 70 ° C for a time sufficient to convert the alumina to colloidal gel, then a drying step of said colloidal gel obtained. US 5 178 849 discloses a process for producing an alpha alumina comprising a step of dispersing an aluminum hydrate having a dispersibility of less than 70%, a step of acidifying the dispersion obtained at a pH below 3.5 to at least partially dissolve the aluminum hydrate, a hydrothermal treatment step of the acid dispersion obtained at a temperature between 150 and 200 ° C, a pressure between Set 20 atm for a duration of between 0, 15 and 4 hours to obtain a colloidal boehmite having a dispersibility greater than 90%.
    [0002] The alumina gel preparation by precipitation is also well known in the prior art. In particular, US Pat. No. 7,790,652 describes the precipitation preparation of an alumina support having a very specific porous distribution, which can be used as a catalyst support in a process for hydroconversion of heavy hydrocarbon feedstocks. The alumina support is prepared according to a method comprising a first step of forming an alumina dispersion by mixing, in a controlled manner, a first aqueous alkaline solution and a first aqueous acidic solution, at least one of said acidic and basic solutions, or both comprising an aluminum compound. The acidic and basic solutions are mixed in such proportions that the pH of the resulting dispersion is between 8 and 11. The acidic and basic solutions are also mixed in quantities which make it possible to obtain a dispersion containing the desired quantity of alumina. in particular, the first step makes it possible to obtain 25 to 35% by weight of alumina with respect to the total amount of alumina formed at the end of the two precipitation stages. The first stage operates at a temperature of between 20 and 40 ° C. When the desired amount of alumina is formed, the temperature of the slurry is raised to a temperature between 45 and 70 ° C, and then the heated slurry is then subjected to a second precipitation step by contacting said slurry with a second alkaline aqueous solution and a second acidic aqueous solution, at least one or both of the two solutions comprising an aluminum compound. Similarly, the pH is adjusted between 8 and 10.5 by the proportions of the acid and basic solutions added and the remaining quantity of alumina to be formed in the second stage is provided by the amounts of the second acid and basic solutions added. The second step operates at a temperature between 20 and 40 ° C. The alumina gel thus formed comprises at least 95% of boehmite. The dispersibility of the alumina gel thus obtained is not mentioned. The alumina gel is then filtered, washed and optionally dried according to methods known to those skilled in the art, without prior heat treatment step, to produce an alumina powder which is then shaped according to the known methods of the skilled person and then calcined to produce the final alumina support. The first precipitation step of the preparation method of US Pat. No. 7,790,652 is limited to a low alumina production of between 25 and 35% by weight, since higher alumina production at the end of the first stage does not allow optimal filtration of the gel obtained. On the other hand, the increase in alumina production in the first step of US Pat. No. 7,790,652 Shell would not allow the gel thus obtained to be shaped. Surprisingly, the applicant has discovered that a specific alumina gel having a high degree of dispersibility, prepared according to a process comprising at least one precipitation step in which at least 40% by weight of alumina in equivalent Al 2 O 3 relative to the total amount of alumina formed at the end of said gel preparation process is formed from the first precipitation step, and a final heat treatment step, and in particular a final ripening step, can be formed. to obtain an amorphous mesoporous alumina exhibiting a specific porous distribution as well as a very high connectivity. An object of the present invention is to provide an amorphous mesoporous alumina with very high connectivity.
    [0003] Another object of the present invention is to provide a process for preparing said alumina by shaping an alumina gel having a high dispersibility and in particular greater than 70% and a crystallite size between 2 and 35 nm.
    [0004] SUMMARY AND OBJECT OF THE INVENTION The subject of the present invention is an amorphous mesoporous alumina having a connectivity (Z) greater than 2.7. An advantage of the invention is to provide an alumina whose porosity is highly connected, i.e. having a very large number of adjacent pores. High connectivity represents an important advantage for the accessibility of the porosity and plays an important role both during the impregnation steps of highly viscous phase-active precursor solutions and for the diffusion of the molecules to be treated during the catalytic reactions using these materials.
    [0005] The present invention also relates to a process for the preparation of said alumina, said process comprising at least the following steps: a) at least a first step of precipitation of alumina, in an aqueous reaction medium, 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, sodium chloride, aluminum, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acid precursors and basic is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a rate of progress of said first step com between 40% and 100%, the degree of progress being defined as the proportion of alumina formed in A1203 equivalent during said first precipitation step relative to the total amount of alumina formed at the end of the precipitation steps, said first precipitation step operating at a temperature between 10 and 50 ° C, and for a period of between 2 minutes and 30 minutes, b) a heat treatment step of the suspension obtained at the end of step a) at a temperature between 50 and 200 ° C for a duration of between 30 minutes and 5 hours to obtain an alumina gel, c) a filtration step of the suspension obtained at the from step b) heat treatment, followed by at least one washing step of the gel obtained, d) a step of drying the alumina gel obtained at the end of step c) to obtain a powder E) a step of shaping the powder obtained at the result of step d) to obtain the green material, f) a heat treatment step of the green material obtained at the end of step e) at a temperature of between 500 and 1000 ° C., not a flow of air containing up to 60% by volume of water.
    [0006] An advantage of the invention is to provide a new process for the preparation of an amorphous mesoporous alumina enabling the shaping of an alumina gel prepared according to a process comprising at least one precipitation step in which at least 40% Alumina weight in Al.sub.2 O.sub.3 equivalent relative to the total amount of alumina formed at the end of said gel preparation process, are formed from the first precipitation step, by virtue of the implementation of a treatment step. thermal and in particular a maturing step for obtaining an alumina gel having improved filterability, and facilitating its shaping.
    [0007] Another advantage of the invention is to provide a novel process for the preparation of an alumina by precipitation which may comprise a single precipitation step, which is inexpensive compared to the conventional alumina preparation methods of the prior art such as for example, sol-gel type preparation processes.
    [0008] Another advantage of the invention is to provide a new process for the preparation of the alumina according to the invention making it possible to obtain an amorphous mesoporous alumina having a specific porous distribution as well as a very high connectivity with respect to the aluminas of the prior art.
    [0009] 10 Definitions and methods of measurement. Throughout the rest of the text, the dispersibility index is defined as the weight percentage of peptised alumina gel that can be dispersed by centrifugation in a polypropylene tube at 3600 G for 10 min.
    [0010] Dispersibility is measured by dispersing 10% boehmite or alumina gel in a water slurry also containing 10% nitric acid based on the boehmite mass. Then, the suspension is centrifuged at 3600G rpm for 10 min. The collected sediments are dried at 100 ° C overnight and weighed. The dispersibility index, denoted ID, is obtained by the following calculation: ID (° / 0) = 100% -mass of 20 dried sediments (%). Throughout the rest of the text, the connectivity of the alumina according to the invention is defined as being the number of pores adjacent to a given pore. The connectivity according to the invention is representative of the totality of the porosity of the alumina and in particular of the totality of the mesoporosity of the alumina, that is to say of all the pores having an average diameter including between 2 and 50 nm. Connectivity is a relative quantity measured according to the procedure described in the Seaton publication (Liu H., Zhang L., Seaton N.A., Chemical Engineering Science, 47, 17-18, pp.4393-4404, 1992). This is a Monte Carlo simulation from nitrogen adsorption / desorption isotherms. These connectivity parameters are based on the theory of percolation. The connectivity is related to the numbers of adjacent pores and represents an advantage for the diffusion during the catalytic reactions of the molecules to be treated.
    [0011] The alumina according to the present invention further has a specific porous distribution, wherein the macroporous and mesoporous volumes are measured by mercury intrusion and the microporous volume is measured by nitrogen adsorption.
    [0012] "Macropores" means pores whose opening is greater than 50 nm. By "mesopores" is meant pores whose opening is between 2 nm and 50 nm, limits included. "Micropores" means pores whose opening is strictly less than 2 nm.
    [0013] In the following description of the invention, the porous distribution measured by mercury porosimetry is determined by mercury porosimeter intrusion according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa) using a voltage surface area of 484 dyne / cm and a contact angle of 140 °. The mooring angle was taken equal to 140 ° according to the recommendations of the book "Techniques of the engineer, treated analysis and characterization, P 1050-5, written by Jean Charpin and Bernard Rasneur". 0.2 MPa the value from which the mercury fills all the intergranular voids, and it is considered that beyond the mercury penetrates the pores of the alumina In order to obtain a better precision, the value of the pore volume total is the value of the total pore volume measured by mercury porosimeter intrusion measured on the sample minus the value of the total pore volume measured by mercury porosimeter intrusion measured on the same sample for a pressure corresponding to 30 psi (approximately 0.2 MPa) The macroporous volume of the catalyst is defined as the cumulative volume of mercury introduced at a pressure of between 0.2 MPa and 30 MPa, corresponding to the volume contained in the pores of diameter The mesoporous volume of the catalyst is defined as the cumulative volume of mercury introduced at a pressure of between 30 MPa and 400 MPa, corresponding to the volume contained in the pores with an apparent diameter of between 2 and 50 nm. The micropore volume 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 transformation of the starting adsorption isotherm as described in the " Adsorption by powders and porous solids. Principles, methodology and applications "written by F. Rouquerol, J. Rouquerol and K. Sing, Academic Press, 1999. The mesopore median diameter (Dp in nm) is also defined as a diameter such that all size pores less than this diameter constitute 50% of the mesoporous volume, measured by mercury porosimetry. The porous distribution measured by nitrogen adsorption was determined by the Barrett-Joyner-Halenda model (BJH). 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, the volume measured for P / Po = 0.99, pressure for which it is assumed that nitrogen has filled all the pores.
    [0014] In the following description of the invention, the term "specific surface" means the specific surface B.E.T. determined by nitrogen adsorption according to ASTM D 3663-78 established from the BRUNAUER-EMMETT-TELLER method described in the journal "The Journal of the American Society", 60, 309, (1938).
    [0015] According to the invention, the amorphous mesoporous alumina has a connectivity of greater than 2.7, preferably of between 2.7 and 10, more preferably of between 2.8 and 10, very preferably preferred between 3 and 9, more preferably between 3 and 8 and even more preferably between 3 and 7.
    [0016] The alumina according to the present invention advantageously has a BET specific surface and a pore volume and in particular mesoporous calibrated. Preferably, the mesoporous alumina is devoid of micropores. The absence of micropores is measured and verified by nitrogen adsorption.
    [0017] Preferably, the alumina advantageously has a BET specific surface area of between 50 and 450 m 2 / g, preferably between 100 and 400 m 2 / g, preferably between 150 and 400 m 2 / g, and very preferably between 150 and 350 m2 / g.
    [0018] Preferably, the alumina advantageously has a mesoporous volume greater than or equal to 0.5 ml / g, preferably between 0.6 and 0.8 ml / g. The mesoporous volume is defined as the volume included in pores having a mean diameter of between 2 and 50 nm inclusive. Preferably, the total pore volume of said alumina measured by mercury porosimetry is between 0.6 and 0.9 ml / g.
    [0019] Preferably, the percentage of volume included in the pores between 2 and 50 nm in size relative to the total pore volume of said alumina, is greater than 50% and preferably between 50 to 75%. Preferably, the percentage of volume comprised in pores greater than 50 nm in size relative to the total pore volume of said alumina is less than 10%, and preferably less than 6%. The median diameter of the mesopores measured by mercury porosimetry of said alumina, determined by volume is advantageously between 8 and 12.5 nm and preferably between 9.0 and 12.5 nm.
    [0020] Preferably, the alumina according to the invention is a non-mesostructured alumina. Another subject of the invention relates to the process for preparing said alumina. According to the invention, said preparation process comprises at least a first step a) of precipitation of alumina, in an aqueous reaction medium, of at least one basic precursor chosen from sodium aluminate and potassium aluminate. , ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, 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 rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium comprised between 8.5 and 10.5 and the flow rate of the aluminum-containing acidic and basic precursor (s) is adjusted so as to obtain a forwarding rate of the first step of between 40 and 100%, the rate of progress being defined as the proportion of alumina f in said step a) of precipitation with respect to the total quantity of alumina formed at the end of the precipitation stage (s) and more generally at the end of the steps of preparation of the gel of alumina, said step a) operating at a temperature between 10 and 50 ° C, and for a duration ccmprise between 2 minutes and 30 minutes. In general terms, the "rate of progress" of the nth precipitation stage is the percentage of alumina formed in Al 2 O 3 equivalent in the said nth stage, relative to the total amount of alumina formed in the first stage of precipitation. resulting from all the precipitation steps and more generally after the steps of preparation of the alumina gel. In the case where the progress rate of said precipitation step a) is 100%, said precipitation step a) generally makes it possible to obtain an alumina suspension having an Al 2 O 3 concentration of between 20 and 100 g. / 1, preferably between 20 and 80 g / l, more preferably between 20 and 50 g / l.
    [0021] Step a) of precipitation The mixture 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 comprises aluminum, or that both basic and acidic precursors include aluminum. Basic precursors comprising aluminum are sodium aluminate and potassium aluminate. The preferred basic precursor is sodium aluminate. Acidic precursors comprising aluminum are aluminum sulphate, aluminum chloride and aluminum nitrate. The preferred acidic precursor is aluminum sulphate.
    [0022] Preferably, the basic precursor (s) and acid (s) are added in said first precipitation step a) in aqueous solutions. Preferably, the aqueous reaction medium is water. Preferably, said step a) operates with stirring.
    [0023] Preferably, said step a) is carried out in the absence of organic additive. The acidic and basic precursors, whether they contain aluminum or not, are mixed, preferably in solution, in the aqueous reaction medium, in such proportions that the pH of the resulting suspension is between 8.5 and 10. 5.
    [0024] In accordance with the invention, it is the relative flow rate of the acidic and basic precursors that they contain of aluminum or not, which is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5. In the preferred case where the basic and acidic precursors are respectively sodium aluminate and aluminum sulphate, the mass ratio of said basic precursor to said acidic precursor is advantageously between 1.6 and 2.05. For the other basic and acidic precursors, whether they contain aluminum or not, the base / acid mass ratios are established by a curve of neutralization of the base by the acid. Such a curve is easily obtained by those skilled in the art.
    [0025] Preferably, said precipitation step a) is carried out at a pH of between 8.5 and 10 and very preferably between 8.7 and 9.9. The acidic and basic precursors are also mixed in amounts to provide a suspension containing the desired amount of alumina, depending on the final alumina concentration to be achieved. In particular, said step a) makes it possible to obtain 40 to 100% by weight of alumina in Al 2 O 3 equivalent relative to the total amount of alumina formed at the end of the precipitation stage or stages. According to the invention, it is the flow rate of the acidic and basic precursor (s) containing aluminum which is adjusted so as to obtain a forwarding rate of the first stage of between 40 and 100%.
    [0026] Preferably, the rate of progress of said precipitation step a) is between 40 and 99%, preferably between 45 and 90% and preferably between 50 and 85%. the amount of advance obtained after step a) of precipitation is less than 100%, a second precipitation step is necessary so as to increase the amount of alumina formed. In the case where a second precipitation step is carried out, the rate of advance is defined as the proportion of alumina formed in equivalent A1203 during said step a) of precipitation with respect to the total amount of alumina formed at the end of the two precipitation steps of the preparation process according to the invention and more generally at the end of the steps of preparation of the alumina gel.
    [0027] Thus, depending on the concentration of alumina targeted at the end of the precipitation step (s), preferably between 20 and 100 g / l, the quantities of aluminum to be provided by the acid and / or basic precursors are calculated and the flow rate of the precursors is adjusted according to the concentration of said added aluminum precursors, the amount of water added to the reaction medium and the rate of progress required for the precipitation step (s). The flow rate of the acidic and / or basic precursor (s) containing aluminum depends on the size of the reactor used and thus on the amount of water added to the reaction medium. Preferably, said precipitation step a) is carried out at a temperature of between 10 and 45 ° C, preferably between 15 and 45 ° C, more preferably between 20 and 45 ° C and very preferably between 20 and 45 ° C. and 40 ° C. It is important that said precipitation step a) operates at a low temperature. In the case where said preparation process according to the invention comprises two precipitation stages, the precipitation step a) is advantageously carried out at a temperature below the temperature of the second precipitation stage.
    [0028] Preferably, said precipitation step a) is carried out for a period of between 5 and 20 minutes, and preferably of 5 to 15 minutes. Step b) of heat treatment According to the invention, said preparation method comprises a step b) of heat treatment of the suspension obtained at the end of step a) of precipitation, said heat treatment step operating at a temperature of temperature between 60 and 200 ° C for a period of between 30 minutes and 5 hours, to obtain the alumina gel. Preferably, said heat treatment step b) is a ripening step.
    [0029] Preferably, said heat treatment step b) operates at a temperature between 65 and 150 ° C, preferably between 65 and 130 ° C, preferably between 70 and 110 ° C, very preferably between 70 and 95 ° C. ° C. Preferably, said heat treatment step b) is carried out for a duration of between 40 minutes and 5 hours, preferably between 40 minutes and 3 hours, and preferably between 45 minutes and 2 hours.
    [0030] Second optional precipitation step According to a preferred embodiment, in the case where the degree of progress obtained at the end of the precipitation step a) is less than 100%, said preparation method preferably comprises a second precipitation step a ') after the first precipitation step.
    [0031] Said second precipitation step makes it possible to increase the proportion of alumina produced. Said second precipitation step a ') is advantageously carried out between said first precipitation step a) and the heat treatment step b). In the case where a second precipitation step is carried out, a step of heating the suspension obtained at the end of the precipitation step a) is advantageously carried out between the two precipitation steps a) and '). Preferably, said step of heating the suspension obtained at the end of step a), carried out between said step a) and the second precipitation step a ') operates 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. Preferably, said heating step is carried out for a period of between 7 and 45 minutes and preferably between 7 and 35 minutes.
    [0032] Said heating step is advantageously carried out according to all the heating methods known to those skilled in the art. According to said preferred embodiment, said method of preparation comprises a second step of precipitation of the suspension obtained at the end of the heating step, said second stage operating by adding to said suspension at least one chosen basic precursor among sodium aluminate, potassium aluminate, ammonia, sodium hydroxide and potassium hydroxide and at least one acidic precursor selected from aluminum sulphate, 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 rate of the acidic and basic precursors is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain an advancement rate of the second stage inclusive ent 0 and 60%, the advancement rate being defined as the proportion of alumina formed in Al 2 O 3 equivalent during said second precipitation step relative to the total amount of alumina formed at the end of the two stages precipitation, more generally at the end of the steps of preparation of the alumina gel and preferably at the end of step a ') of the preparation process according to the invention, said step operating at a temperature between 40 and 90 ° C, and for a period of time between 2 minutes and 50 minutes. As in the first precipitation step a), the addition to the heated suspension of at least one basic precursor and at least one acidic precursor requires either that at least the basic precursor or the acidic precursor comprises aluminum, the two basic and acidic precursors include aluminum. Basic precursors comprising aluminum are sodium aluminate and potassium aluminate. The preferred basic precursor is sodium aluminate. Acidic precursors comprising aluminum are aluminum sulphate, aluminum chloride and aluminum nitrate. The preferred acidic precursor is aluminum sulphate.
    [0033] Preferably, said second precipitation step operates with stirring. Preferably, said second step is carried out in the absence of organic additive. The acidic and basic precursors, whether they contain aluminum or not, are mixed, preferably in solution, in the aqueous reaction medium, in such proportions that the pH of the resulting suspension is between 8.5 and 10.5. Preferably, the basic precursor (s) and acid (s) are added in said second precipitation step a ') in aqueous solutions. As in step a) of precipitation, it is the relative flow rate of the acidic and basic precursors that they contain aluminum or not, which is chosen so as to obtain a pH of the reaction medium of between 8. , 5 and 10.5. In the preferred case where the basic and acidic precursors are respectively sodium aluminate and aluminum sulphate, the mass ratio of said basic precursor to said acidic precursor is advantageously between 1.6 and 2.05. For the other basic and acidic precursors, whether they contain aluminum or not, the base / acid mass ratio is established by a curve of neutralization of the base by the acid. Such a curve is easily obtained by those skilled in the art. Preferably, said second precipitation step is carried out at a pH of between 8.5 and 10 and preferably between 8.7 and 9.9.
    [0034] The acidic and basic precursors are also mixed in amounts to provide a slurry containing the desired amount of alumina, depending on the final alumina concentration to be achieved. In particular, said second precipitation step makes it possible to obtain from 0 to 60% by weight of alumina in Al.sub.2 O.sub.3 equivalent relative to the total amount of alumina formed at the end of the two precipitation stages and preferably at the from step a '). Just as in step a) of precipitation, it is the flow rate of the acidic and basic precursor (s) containing aluminum which is adjusted so as to obtain a progress rate of the second stage of between 0 and 60.degree. %, the advancement rate being defined as the proportion of alumina formed in Al 2 O 3 equivalent during said second precipitation step relative to the total amount of alumina formed at the end of the two precipitation steps of the process according to invention and preferably at the end of step a '). Preferably, the rate of advancement of said second precipitation step a) is from 1 to 60, preferably from 10 to 55 (3/0 and preferably from 15 to 55%. concentration of alumina referred to after the precipitation step (s), preferably between 20 and 100 g / I, the amounts of aluminum to be provided by the acid precursors and / or basic are calculated and the flow rate of 20 precursors is adjusted according to the concentration of said added aluminum precursors, the amount of water added to the reaction medium and the rate of progress required for each of the precipitation steps, as well as in step a) of precipitation , the flow rate of the acid-containing and / or basic precursor (s) containing aluminum depending on the size of the reactor used and thus the amount of water added to the reaction medium. For example, if one works in a reactor of 3 1 and that one aims at slurry of alumina with a final concentration of Al 2 O 3 of 50 g / l, the targeted rate of advancement is 50%. equivalent A1203 for the first precipitation stage. Thus, 50% of the total alumina must be provided during step a) of precipitation. The precursors of aluminas are sodium aluminate at a concentration of 155 g / l in Al 2 O 3 and aluminum sulphate at a concentration of 102 g / l in Al 2 O 3. The precipitation pH of the first stage is set at 9, And the second to 9. The amount of water added to the reactor is 622 ml.
    [0035] For the first step a) of precipitation operating at 30 ° C. and for 8 minutes, the flow rate of aluminum sulphate should be 10.5 ml / min and the flow rate of sodium aluminate is 13.2 ml. / min. The mass ratio of sodium aluminate to aluminum sulfate is therefore 1.91. For the second precipitation stage, operating at 70 ° C., for 30 minutes, the aluminum sulfate flow rate should be 2.9 ml / min and the sodium aluminate flow rate should be 3.5 ml / min. . The mass ratio of sodium aluminate to aluminum sulfate is therefore 1.84. Preferably, the second precipitation step is carried out at a temperature between 40 and 80 ° C, preferably between 45 and 70 ° C and very preferably between 50 and 70 ° C. Preferably, the second precipitation step is carried out for a period of between 5 and 45 minutes, and preferably of 7 to 40 minutes. The second precipitation step generally makes it possible to obtain a suspension of alumina having an Al 2 O 3 concentration of between 20 and 100 g / l, preferably between 20 and 80 g / l, preferably between 20 and 50 g. / 1. In the case where said second precipitation step is carried out, said preparation process also advantageously comprises a second heating step of the suspension obtained at the end of said second precipitation step at a temperature of between 50 and 95 ° C. C and preferably between 60 and 90 ° C. Preferably, said second heating step is carried out for a period of between 7 and 45 minutes. Said second heating step is advantageously carried out according to all the heating methods known to those skilled in the art. Said second heating step makes it possible to increase the temperature of the reaction medium before subjecting the suspension obtained in step b) of heat treatment. Filtration step c) According to the invention, the process for the preparation of alumina according to the invention also comprises a step c) of filtration of the suspension obtained at the end of step b) of heat treatment, followed by at least one washing step of the gel obtained. Said filtration step is carried out according to the methods known to those skilled in the art.
    [0036] The filterability of the suspension obtained at the end of step a) of precipitation or of the two precipitation steps is improved by the presence of said final heat treatment step b) of the suspension obtained, said heat treatment step promoting the productivity of the process according to the invention as well as an extrapolation of the process to the industrial level. Said filtration step is advantageously followed by at least one washing step with water and preferably from one to three washing steps, with a quantity of water equal to the amount of filtered precipitate.
    [0037] The sequence of steps a) and c) and optionally of the second precipitation step, the second heating step and the optional filtration step, makes it possible to obtain a specific alumina gel having a subscript. of dispersibility greater than 70%, a crystallite size of between 1 and 35 nm and a sulfur content of between 0.001% and 2% by weight and a sodium content of between 0.001% and 2% by weight, the weight percentages being based on the total weight of alumina gel, the alumina gel thus obtained has a dispersibility index of between 70 and 100%, preferably between 80 and 100%, very preferably between 85 and 100% and even more preferably between 90 and 100%.
    [0038] Preferably, the alumina gel thus obtained has a crystallite size of from 2 to 35 nm. Preferably, the alumina gel thus obtained comprises a sulfur content of between 0.001% (3/0 and 1% by weight, preferably between 0.001% and 0.40% by weight, very preferably between 0.003 and 0.33% by weight). 3/0 weight, and more preferably between 0.005 and 0.25 (3/0) weight, preferably the alumina gel thus obtained comprises a sodium content of between 0.001 (3/0 and 1% by weight, preferably between 0.001 and 0.15 (3/0 weight, very preferably between 0.0015 and 0.10% by weight, and 0.002 and 0.040% by weight.
    [0039] In particular, the alumina gel or the boehmite in powder form according to the invention is composed of crystallites whose size, obtained by the Scherrer formula in X-ray diffraction according to the crystallographic directions (020) and (120) is respectively between 2 and 20 nm and between 2 and 35 nm.
    [0040] Preferably, the alumina gel according to the invention has a crystallite size in the crystallographic direction (020) of between 2 and 15 nm and a crystallite size in the crystallographic direction (120) of between 2 and 35 nm. .
    [0041] X-ray diffraction on alumina or boehmite gels was performed using the conventional powder method using a diffractometer. Scherrer's formula is a formula used in X-ray diffraction on powders or polycrystalline samples which connects the width at half height of the diffraction peaks to the size of the crystallites. It is described in detail in the reference: Appl. Cryst. (1978). 11, 10 102-113 Scherrer after sixty years: A survey and some new results in the determination of crystallite size, J. I. Langford and A. J. C. Wilson. The alumina gel thus prepared and having a high degree of dispersibility 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 extrusion, granulation and technique known as oil drop according to the English terminology. Step d) of drying According to the invention, the alumina gel obtained at the end of the filtration step c) is dried in a drying step d) to obtain a powder. Said drying step is advantageously carried out at a temperature of between 20 and 50 ° C. and for a period of time ranging from 1 day to 3 weeks or by atomization.
    [0042] In the case where said drying step d) is carried out at a temperature of between 20 and 50 ° C. and for a duration of between 1 day and 3 weeks, said drying step d) can advantageously be carried out in a closed oven. and ventilated, preferably said drying step operates at a temperature between 25 and 40 ° C, and for a period of time between 3 days and two weeks.
    [0043] In the case where said drying step d) is carried out by atomization, the cake obtained at the end of the heat treatment step optionally followed by a filtration step is resuspended. Said suspension is then sprayed into fine droplets in a vertical cylindrical chamber 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 driven by the heat flow to a cyclone or a bag filter that will separate the air from the powder. Preferably, in the case where said drying step d) is carried out 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. Step e) Shaping In accordance with the invention, the powder obtained at the end of the drying step d) is shaped in a step e) to obtain a green material. By raw material is meant the material shaped and having not undergone any heat treatment steps. Preferably, said forming step e) is carried out by extrusion kneading, by pelletization, by the method of dropwise coagulation (oil-drop), by rotary-plate granulation or by any other well-known method of the invention. skilled person. In a very preferred manner, said shaping step e) is carried out by extrusion kneading. Step f) Heat Treatment According to the invention, the green material obtained at the end of the shaping step e) is then subjected to a heat treatment step f) at a temperature of between 500 and 1000 ° C. , for a period of between 2 and 10 h, in the presence or absence of air flow containing up to 60% water volume.
    [0044] Preferably, said heat treatment step f) operates at a temperature of between 540 ° C and 850 ° C. Preferably, said heat treatment step f) operates for a duration of between 2 h and 10 h. Said heat treatment step f) allows the transition from boehmite to final alumina. The preparation method according to the invention makes it possible to obtain an amorphous mesoporous alumina having a connectivity of greater than 2.7 and a controlled mesoporosity having good thermal and chemical stability, having a centered uniform size distribution of the mesopores. and controlled, and a specific surface and a pore volume and in particular mesoporous calibrated. The mesoporous alumina prepared according to the method of the invention is devoid of micropores. It advantageously has a BET surface area of between 50 and 450 m 2 / g, and a mesoporous volume greater than or equal to 0.5 ml / g, preferably between 0.6 and 0.8 ml / g. The invention is illustrated by the following examples, which in no way present a limiting character.
    [0045] Examples: Example 1: (comparative) A commercial Pural SB3 boehmite is used in powder form. The shaping of this is carried out in the first step by acid mixing, with an aqueous acid solution (Ta: nitric acid content of 3% w / dry mass introduced into the kneading) for 0 to 60 min. . Then follows a basic mixing neutralization rate (Tb: 50% weight / HNO3). The paste obtained is extruded through a 2 mm trilobal die. The extrudates obtained are dried at 100 ° C. overnight and then calcined for 2 hours at 600 ° C. SBET powder starting gel (m2 / g) VPT Hg (ml / g) Dp (Hg) (nm) commercial 191 0.51 10.4 2.3 Example 2 (comparative): A synthesis of a gel is carried out of alumina according to a non-conforming preparation process in that the preparation method according to example 2 does not comprise a heat treatment stage of the suspension obtained at the end of the precipitation steps and in that the first precipitation step a) does not produce an amount of alumina higher than 40% relative to the total amount of alumina formed at the end of the second precipitation step. Example 2 is carried out according to the preparation method described in US Pat. No. 7,790,562. The synthesis is carried out in a 7L reactor and a final suspension of 5L in two precipitation stages. The amount of water added to the reactor is 3868 ml.
    [0046] The final alumina concentration referred to is 30 g / l.
    [0047] A first step of co-precipitating aluminum sulphate Al2 (SO4) and sodium aluminate NaA100 is carried out at 30 ° C and pH = 9.3 for a period of 8 minutes. The concentrations of the aluminum precursors used are as follows: Al 2 (SO 4) = 102 g / l in Al 2 O 3 and Naa 100 to 155 g / l in Al 2 O 3. The agitation is 350 rpm throughout the synthesis. A solution of aluminum sulphate Al2 (SO4) is added continuously for 8 minutes at a flow rate of 19.6 ml / min to a solution of sodium aluminate NaA100 in a weight ratio base / acid = 1.80 to adjust the pH to a value of 9.3. The temperature of the reaction medium is maintained at 30 ° C. A suspension containing a precipitate of alumina is obtained. As the final concentration of alumina is 30 g / l, the flow rate of aluminum sulphate precursors Al 2 (SO 4) and sodium aluminum aluminate NaA 100 introduced in the first precipitation stage are respectively 19.6 ml / min. and 23.3 ml / min. These flow rates of acid and basic precursors containing aluminum make it possible to obtain at the end of the first precipitation step a degree of progress of 30%. The suspension obtained is then subjected to a temperature rise of 30 to 57 ° C.
    [0048] A second step of co-precipitation of the suspension obtained is then carried out by adding Al 2 (SO 4) aluminum sulphate at a concentration of 102 g / l of Al 2 O 3 and of sodium aluminate NaAl 3 at a concentration of 155 g / l. I to A1203. A solution of aluminum sulphate Al2 (SO4) is therefore added continuously to the heated suspension obtained at the end of the first precipitation step for 30 minutes at a flow rate of 12.8 ml / min at a solution of sodium aluminate NaA100 in a weight ratio base / acid = 1.68 so as to adjust the pH to a value of 8.7. The temperature of the reaction medium in the second step is maintained at 57 ° C. A suspension containing a precipitate of alumina is obtained. Since the final concentration of alumina is 30 g / l, the flow rate of aluminum sulphate precursors Al 2 (SO 4) and aluminum aluminate NaA 100 containing aluminum introduced into the second precipitation stage are respectively 12.8 ml / ml. min and 14.1 ml / min. These flow rates of aluminum-containing basic and basic precursors make it possible to obtain at the end of the second precipitation stage a 70% degree of advance.
    [0049] The suspension thus obtained does not undergo a ripening step. The suspension obtained is then filtered by displacement of water on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 5 l of distilled water at 70 ° C. The filtration and washing time is 4 hours. The characteristics of the alumina gel thus obtained are summarized in Table 2. Table 2: characteristics of the alumina gel obtained according to Example 2. Example 2 Dispersibility index Ta = 10 ° / 0 (° / 0) 60 Size (020) (nm) 2.9 Size (120) (nm) 4.1 Sodium Na (ppm) 0.011 S sulfur (ppm) 0.057 Filtration time 4 h The alumina gel is then spray-dried with a temperature 250 ° C inlet and 130 ° C outlet.
    [0050] The dried alumina gel is introduced into a Brabender type mixer. Acidified water with nitric acid at a total acid content of 3%, expressed by weight relative to the mass of dried gel introduced into the kneader, is added in 5 minutes during mixing at 20 rpm. min. The acid mixing is continued for 15 minutes. A neutralization step is then carried out by adding an ammoniacal solution in the kneader, at a neutralization rate of 50%, expressed by weight of ammonia relative to the amount of nitric acid introduced into the kneader for the acidification step. The kneading is continued for 3 minutes. The paste obtained is then extruded through a 2 mm trilobal die. The extrudates obtained are dried at 100 ° C. overnight and then calcined for 2 hours at 600 ° C.
    [0051] The characteristics of the alumina formed are reported in Table 3: Table 3: Characteristics of the alumina obtained according to Example 2. SBET (m2 / g) Example 2 230 0.78 11.9 2.5 VPT (Hg) (ml / g) Dp (Hg) (nm) Example 3 (Comparative): The alumina synthesis is carried out according to a preparation method not according to the invention in that the precipitation step is performed at high temperature, that is to say at a temperature of 60 ° C. The agitation is 350 rpm throughout the synthesis.
    [0052] The synthesis is carried out in a reactor of 5 liters and comprises a single precipitation stage and a stage of ripening of the suspension obtained. The final target alumina concentration is 50 g / I. A step of precipitating aluminum sulphate Al2 (SO4) and sodium aluminate NaA100 is carried out at 60 ° C and pH = 10.2 during a 20-minute cure. The concentrations of the aluminum precursors used are as follows: Al 2 (SO 4) = 102 g / l in Al 2 O 3 and NaA 100 to 155 g / l in Al 2 O 3 A solution of aluminum sulphate Al 2 (SO 4) is added continuously for 30 minutes at a flow rate of 25.9 ml / min to a solution of sodium aluminate NaA100 in a mass ratio base / acid = 2.0 so as to adjust the pH to a value of 10.2. All precursors are contacted at a temperature of 60 ° C. A suspension containing a precipitate of alumina is obtained. As the final concentration of alumina is 50 g / l, the flow rate of aluminum sulphate precursors Al2 (SO4) and aluminum aluminate NaA100 containing aluminum introduced in the first precipitation stage are respectively 25.9 ml / min and 34.1 ml / min. These flow rates of acidic and basic precursors containing aluminum make it possible to obtain at the end of the first precipitation step a degree of advance of 100%. The suspension obtained is then subjected to a temperature rise of 60 to 90 ° C.
    [0053] The suspension then undergoes a ripening step in which it is held at 90 ° C for 60 minutes.
    [0054] The suspension obtained is then filtered by displacement of water on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 3.5 l of distilled water at 70.degree. The filtration and washing time is 3h.
    [0055] The characteristics of the alumina gel thus obtained are summarized in Table 4. Table 4: characteristics of the alumina gel obtained according to Example 3. Example 3 Dispersibility index Ta (10% (° / 0)) 0 Size (020) (nm) 2.9 Size (120) (nm) 3.4 Sodium Na (° / 0) 0.0068 Sulfur S (° / 0) 0.042 Filtration Time 3 hrs The alumina gel is then dried by atomization with an inlet temperature of 250 ° C and output of 130 ° C. The dried alumina gel is then introduced into a Brabender type mixer. Acidified water with nitric acid at a total acid content of 3%, expressed by weight relative to the mass of dried gel introduced into the kneader, is added in 5 minutes, during a 20% stirring. revolutions / min. The acid mixing is continued for 15 minutes. No cohesive paste is obtained. No extrudates of alumina could thus be obtained and the measurement of connectivity could not be carried out.
    [0056] Example 3 not in accordance with the invention demonstrates the importance of operating during the low temperature precipitation stage and in particular during the first precipitation stage. Thus, a precipitation step carried out at a temperature of 70 ° C., outside the ranges claimed, does not make it possible to obtain a dispersible gel. In contrast, the 10% dispersion of the alumina gel thus obtained in a water suspension also containing 10% nitric acid relative to the alumina gel mass, followed by centrifugation of the 3600G suspension for 10 min, leads to 100% sediment. Thus, the method of preparation according to Example 3 operating at high temperature in the precipitation step does not allow the shaping of the alumina gel obtained and therefore does not allow to obtain extrudates of alumina.
    [0057] EXAMPLE 4 (according to the invention) The alumina synthesis is carried out according to a preparation method according to the invention in a reactor of 7 liters and a final suspension of 5L in 3 stages, two stages of precipitation followed by a ripening stage. The final alumina concentration is 45g / I. The amount of water added to the reactor is 3267 ml. The agitation is 350 rpm throughout the synthesis.
    [0058] A first step of co-precipitation in water, aluminum sulphate Al2 (SO4) and sodium aluminate NaA100 is carried out at 30 ° C and pH = 9.5 for a period of 8 minutes. The concentrations of aluminum precursors used are as follows: Al 2 (SO 4) = 102 g / l in Al 2 O 3 and NaA 100 at 155 g / l in Al 2 O 3 A solution of aluminum sulphate Al 2 (SO 4) is added continuously for 8 minutes at a flow rate of 69.6 ml / min to a solution of sodium aluminate NaA100 at a flow rate of 84.5 ml / min in a mass ratio acid / acid = 1.84 so as to adjust the pH to a value 9.5. The temperature of the reaction medium is maintained at 30 ° C. A suspension containing a precipitate of alumina is obtained. As the final concentration of alumina is 45 g / l, the flow rate of aluminum sulphate precursors Al 2 (SO 4) and aluminum aluminate NaA 100 containing aluminum introduced in the first precipitation stage are respectively 69.6 ml / ml. min and 84.5 ml / min. These flow rates of aluminum-containing acidic and basic precursors make it possible to obtain at the end of the first precipitation step an advancement rate of 72%. The resulting suspension is then subjected to a temperature rise of 30 to 68 ° C.
    [0059] A second step of co-precipitation of the suspension obtained is then carried out by adding aluminum sulphate Al 2 (SO 4) at a concentration of 102 g / l of Al 2 O 3 and of sodium aluminate NaAl 3 at a concentration of 155 g / l in A1203. A solution of aluminum sulphate Al2 (SO4) is therefore added continuously to the heated suspension obtained at the end of the first precipitation step for 30 minutes at a flow rate of 7.2 ml / min. sodium aluminate NaA100 in a weight ratio base / acid = 1.86 so as to adjust the pH to a value of 9. The temperature of the reaction medium in the second step is maintained at 68 ° C.
    [0060] A suspension containing a precipitate of alumina is obtained. As the final concentration of alumina is 45 g / L, the flow rate of aluminum sulphate precursors Al 2 (SO 4) and aluminum aluminate NaA 100 containing aluminum introduced in the second precipitation stage are respectively 7.2 ml / min. and 8.8 ml / min. 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 28%. The resulting suspension is then subjected to a temperature rise of 68 to 90 ° C.
    [0061] The slurry then undergoes a heat treatment step in which it is held at 90 ° C for 60 minutes. The suspension obtained is then filtered by displacement of water on a sintered Buchner type tool and the alumina gel obtained is washed 3 times with 5 l of distilled water. Filtration time 15 and washes is 3h. The characteristics of the alumina gel thus obtained are summarized in Table 5. Table 5: Characteristics of the alumina gel obtained according to Example 4. Example 4: Dispersibility index Ta = 10 ° / 0 (° / 0) 100 Size (020) (nm) 2.8 Size (120) (nm) 3.5 Sodium Na (° / 0) 0.074 S sulfur (° / 0) 0.0364 Filtration time 3h A gel having a dispersibility index 100% is thus obtained. The resulting alumina gel is then spray-dried with an inlet temperature of 250 ° C and an exit temperature of 130 ° C. The gel dried by atorreation is called Gel No. 1.
    [0062] The alumina gel obtained according to Example 4 was also dried in a ventilated study at 35 ° C. for 4 days. The dried gel in an oven is called Gel No. 2. Dried alumina gels Nos. 1 and 2 are then respectively introduced into a Brabender-type mixer. Acidified water with nitric acid at a total acid level of 3%, expressed by weight relative to the mass of dried gel introduced into the kneader, is added over a period of 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 ammoniacal solution in the kneader, at a neutralization rate of 50%, expressed by weight of ammonia relative to the amount of nitric acid introduced into the kneader for the acidification step. The kneading is continued for 3 minutes. The paste obtained is then extruded through a 2 mm trilobal die. The extrudates obtained are dried at 100 ° C. overnight and then calcined for 2 hours at 600 ° C. The characteristics of the alumina formed are reported in Table 6: Table 6: Characteristics of the alumina gel obtained according to Example 4. Gel No. 1 No. 2 Temp. SBET drying (m2 / g) VPT (Hg) (ml / g) Dp (Hg) (nm) Atomization 35 ° C 289 292 0.68 0.69 9.7 9.8 6.5 6 The treatment stage Thermal gel obtained according to the preparation method according to the invention allows a good gel filterability that is to say a filtration time compatible with an extrapolation at the industrial level of the process, thus allowing a better productivity of said process. Furthermore, the preparation process according to the invention allows the shaping of an alumina gel in which 70% by weight of alumina with respect to the total amount of alumina formed at the end of said preparation process are formed from the first precipitation stage.
    [0063] The alumina extrudates obtained have a very high connectivity whatever the drying mode used. Example 5 (Comparative): Example 5 not in accordance with the invention is carried out in the same manner and under the same operating conditions as Example 4 according to the invention, with the difference that the suspension obtained at the end of the second precipitation stage does not undergo a ripening stage.
    [0064] The suspension obtained at the end of the second precipitation step is filtered by displacement of water on a sintered Buchner type tool and the resulting alumina gel is washed 3 times with 3.51 of distilled water. The filtration and washing time is 24 hours.
    [0065] The characteristics of the alumina gel thus obtained are summarized in Table 7. Table 7: Characteristics of the alumina gel obtained according to Example 5. Example 5 Dispersibility index Ta = 10 ° / 0 (° / 0) 100 Size (020) (nm) 2.8 Size (120) (nm) 3.5 Sodium Na (° / 0) 0.442 S sulfur (° / 0) 0.0284 Filtration time 24h 10 The alumina gel as well got could not be formatted. Indeed drying in an oven at 120 ° C leads to a powder impossible to burn by mixing extrusion or oil drop. Example 5 not in accordance with the invention highlights the importance of the implementation of the heat treatment step between the precipitation step and the drying step of the gel obtained. 20 25 30 28
    权利要求:
    Claims (14)
    [0001]
    REVENDICATIONS1. Amorphous mesoporous alumina having connectivity (Z) greater than 2.7, the connectivity being determined from nitrogen adsorption / desorption isotherms.
    [0002]
    2. Alumina according to claim 1 having a connectivity between 3 and 7.
    [0003]
    3. Alumina according to one of claims 1 or 2 having a BET specific surface area of between 50 and 450 m2 / g.
    [0004]
    4. Alumina according to one of claims 1 to 3 having a mesoporous volume greater than or equal to 0.5 ml / g measured from the nitrogen saturation adsorption isotherm.
    [0005]
    5. Process for the preparation of said alumina according to one of claims 1 to 4, said process comprising at least the following steps: a) at least a first step of precipitation of alumina, in an aqueous reaction medium, 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, sodium chloride, aluminum, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of the basic or acidic precursors comprises aluminum, the relative flow rate of the acid precursors and basic is chosen so as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a rate of progress of said first step between 40 and 100%, the e advancement rate being defined as being the proportion of alumina formed in equivalent A1203 during said first precipitation step relative to the total amount of alumina formed at the end of the precipitation step or steps, said first step precipitating operating at a temperature between 10 and 50 ° C, and for a period of between 2 minutes and 30 minutes, b) a heat treatment step of the suspension obtained at the end of step a), a at a temperature between 50 and 200 ° C for a duration of between 30 minutes and 5 hours, C) a filtration step of the suspension obtained at the end of the heat treatment step b), followed by at least one step of washing the gel obtained, d) a step of drying the alumina gel obtained at the end of step c) to obtain a powder, e) a step of shaping the powder obtained at the from step d) to obtain the raw material, f) a heat treatment step of the raw material obtained at the end of step e) at a temperature of between 500 and 1000 ° C., in the presence or absence of airflow containing up to 60% by volume of water. 10
    [0006]
    The process of claim 5 wherein the basic precursor is sodium aluminate.
    [0007]
    7. Preparation process according to one of claims 5 or 6 wherein the acidic precursor is aluminum sulphate.
    [0008]
    8. Preparation process according to one of claims 5 to 7 wherein the mass ratio of said basic precursor on said acid precursor is between 1.6 and 2.05. 20
    [0009]
    9. Preparation process according to one of claims 5 to 8 wherein the rate of progress of said precipitation step a) is between 45 and 90%.
    [0010]
    10. Preparation process according to one of claims 5 to 9 wherein, in the case where the advancement rate obtained at the end of the first step a) of precipitation is less than 100%, said preparation process comprises a second precipitation step a ') after the first precipitation step.
    [0011]
    11. Preparation process according to claim 10 wherein a step of heating the suspension obtained at the end of step a) of precipitation is carried out between the two precipitation steps a) and a '), said heating step operating at a temperature between 20 and 90 ° C and for a period of between 7 and 45 minutes.
    [0012]
    12. A method of preparation according to one of claims 10 or 11 wherein said second precipitation step a ') of the suspension obtained at the end of the heating step, operates by adding in said suspension 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 sulphate, 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 acidic and basic precursors is chosen in such a way as to obtain a pH of the reaction medium of between 8.5 and 10.5 and the flow rate of the acidic and basic precursor (s) containing aluminum is adjusted so as to obtain a degree of progress. the second step between 0 and 60%, led the progress rate of the second step being defined as the proportion of alumina formed in equivalent A1203 during said second precipitation step a ') with respect to the total amount of alumina formed at the end of the step a ') of the preparation process, said second step a') operating at a temperature between 40 and 90 ° C, and for a period of between 2 minutes and 50 minutes. 15
    [0013]
    13. Preparation process according to claim 12 wherein the mass ratio of said basic precursor on said acid precursor is between 1.6 and 2.05, the basic precursors and acid being respectively sodium aluminate and aluminum sulphate . 20
    [0014]
    14. Preparation process according to one of claims 12 or 13 wherein the second precipitation step a ') is carried out at a temperature between 45 and 70 ° C.
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    公开号 | 公开日
    EP3154677B1|2019-02-06|
    RU2683778C2|2019-04-02|
    DK3154677T3|2019-05-06|
    BR112016028740B1|2021-07-20|
    BR112016028740A2|2017-08-22|
    FR3022238B1|2016-07-29|
    RU2017100949A|2018-07-16|
    US20170121180A1|2017-05-04|
    CN106604907B|2020-10-30|
    US10364158B2|2019-07-30|
    JP2017518252A|2017-07-06|
    JP6568876B2|2019-08-28|
    WO2015189202A1|2015-12-17|
    RU2017100949A3|2018-10-18|
    CN106604907A|2017-04-26|
    EP3154677A1|2017-04-19|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1455423A|FR3022238B1|2014-06-13|2014-06-13|AMORPHOUS AMORPHOUS ALUMINA HAVING HIGH CONNECTIVITY AND PROCESS FOR PREPARING THE SAME|FR1455423A| FR3022238B1|2014-06-13|2014-06-13|AMORPHOUS AMORPHOUS ALUMINA HAVING HIGH CONNECTIVITY AND PROCESS FOR PREPARING THE SAME|
    US15/318,375| US10364158B2|2014-06-13|2015-06-09|Amorphous mesoporous alumina with high connectivity and production method thereof|
    PCT/EP2015/062828| WO2015189202A1|2014-06-13|2015-06-09|Amorphous mesoporous alumina with high connectivity and production method thereof|
    JP2016572480A| JP6568876B2|2014-06-13|2015-06-09|Amorphous mesoporous alumina having high connectivity and method for producing the same|
    CN201580031630.8A| CN106604907B|2014-06-13|2015-06-09|Amorphous mesoporous alumina having high connectivity and method of making same|
    RU2017100949A| RU2683778C2|2014-06-13|2015-06-09|Amorphous mesoporous alumina with high connectivity and production method thereof|
    EP15727662.7A| EP3154677B1|2014-06-13|2015-06-09|Amorphous mesoporous alumina with high connectivity and production method thereof|
    DK15727662.7T| DK3154677T3|2014-06-13|2015-06-09|AMORFT MESOPOROST ALUMINA WITH HIGH CONNECTIVITY AND PROCEDURE FOR PRODUCING THEREOF|
    BR112016028740-1A| BR112016028740B1|2014-06-13|2015-06-09|PREPARATION PROCESS OF AN AMORPHIC MESOPOROSAL ALUMINA|
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