FR2936514A1 - ZIRCONIUM HYDRATE POWDER - Google Patents

Abstract

Process for producing a powder of zirconium hydrate and / or hafnium particles, doped or not, and mixtures thereof, said process comprising a step of basic hydrolysis of a powder of starting particles into a derivative of zirconium and / or hafnium of formula M (OH) (N ') (OH), M being Zr, Hf, or a mixture of Zr and Hf, N' being an anion or a mixture of anions, the indices x and y being strictly positive numbers, z being a positive or zero number, said material having a solubility in water at a temperature below 20 ° C of less than 10 mol / l, said derivative being dopable or non-dopable, and said starting particles being composed of base particles, aggregated or not, having a sphericity index of less than 0.6. Application to catalysis and filtration

Description

TECHNICAL FIELD The invention relates to a method of manufacturing a powder intended in particular to catalyze a chemical reaction or filtration. The invention also relates to a powder manufactured or capable of being manufactured by such a method. More generally, the invention relates to a zirconium and / or hafnium derivative powder, a zirconium and / or hafnium hydrate powder and a zirconium and / or hafnium oxide powder. The invention finally relates to the use of a powder according to the invention in certain applications, in particular catalysis and filtration.

STATE OF THE ART Catalysis concerns numerous reactions, in various technical fields, in particular environmental applications, petrochemistry, or fine chemistry. It consists in modifying the speed of a chemical reaction by bringing the reactants of this reaction into contact with a catalyst, for example platinum, which does not appear in the reaction balance. Generally the catalyst is previously deposited on a support, for example in the form of a powder or a body made from such a powder. The powder may also sometimes serve itself as a catalyst. Filtration of fluids also concerns many applications, and in particular the filtration of liquids or gases at high temperatures. For this purpose, the fluids pass through a powder or body made from a powder so that the materials to be filtered are retained by the interstices between the particles, related to their morphology, or in the pores of these particles. In a catalysis application, the particles must have a maximum specific surface in order to increase the contact area between the catalyst and the reactants, whether the particles are used as a catalyst support or as a catalyst themselves. In an application to filtration, a minimal pressure drop is sought during the passage of the fluid to be filtered. In these applications, the particles can also be subjected to high temperatures or severe thermomechanical stresses.

Particles and processes for their manufacture are disclosed in particular in the following documents: FR 2 662 434 relates to the manufacture of monoclinic zirconia whiskers by hydrothermal synthesis. These whiskers are of micrometric dimensions (about 5 m for the examples cited) and are dense due to a hydrothermal treatment temperature of between 300 ° C and 700 ° C.

EP 0 207 469 relates to the production of crystals of zirconia, sulphate-doped zirconia or zirconium hydrate, optionally doped with sulphate, these crystals being in lamellar form with a thickness of less than 50 nm. The process for producing these crystals comprises heating between 110 ° C. and 350 ° C. an acidic aqueous solution (pH <2) of a soluble zirconium salt and sulphates, followed by calcination at a temperature greater than 600 ° C or a desulfation treatment at a temperature between 70 and 110 ° C. EP 0 233 343 relates to the production of ultrafine particles of monoclinic zirconia in the form of elementary fibers with a diameter of less than 5 nm and agglomerated in the form of heaps having a width of between 30 and 200 nm and a length of between 200 nm. and 1 m. The article Zirconia needles synthesized hexagonal swollen liquid crystals "Chemistry Of Materials, 2004, vol 16, pp 4187-4199, describes obtaining needles of millimetric or even centimeter size, having pores of 20 nm, and made up of smaller needles.

There is a continuing need for new particles with high specific surface areas and / or new shapes. There is also a need for particles capable of withstanding high thermal stresses, for example the stresses encountered during the combustion of high temperature gases.

An object of the present invention is to meet, at least partially, one or more of these needs.

SUMMARY OF THE INVENTION Methods According to a first main embodiment, the invention proposes a method for manufacturing a particle powder, comprising the following successive steps: a) preparation of an acidic mother liquor by mixing at least or even by mixing only: [1] a polar solvent; [2] a first reagent, preferably acid-soluble in said solvent, providing Zr'- and / or Hf + ions; [3] a second reagent providing anionic groups; [4] an additive selected from the group consisting of anionic surfactants; amphoteric surfactants; cationic surfactants, carboxylic acids and their salts; nonionic surfactants selected from the group of compounds of formula RCO2R 'and RCONHR' and mixtures thereof, R and R 'being aliphatic, aromatic and / or alkylaromatic carbon chains; and their mixtures; [5] optionally, another non-ioric surfactant; [6] optionally a blowing agent; heating the mother liquor so as to precipitate the Zr + and / or Hf4-ions and the anionic groups in the form of a primary derivative of zirconium and / or hafnium, and optionally drying; optionally converting the primary derivative into a secondary derivative of zirconium and / or hafnium by substitution of said anionic groups by other anionic groups, called anionic substitution groups, and optionally drying; optionally, basic hydrolysis of said primary or secondary derivative; optionally, calcination (step el)) or hydrothermal treatment (step e2)) of the primary derivative obtained at the end of step b), of. secondary derivative obtained at the end of step c), or of the hydrate obtained at the end of step d), so as to obtain an oxide of zirconium and / or hafnium, and optionally drying. As will be seen in more detail in the remainder of the description, the inventors have discovered that the addition of the additive leads, in a simple and effective manner, to obtain particles having a morphology or advantageous properties. The optional steps make it possible to transform these particles into other equally useful particles. B) 20 c) 25 d) e) Steps a) and b), or even c), make it possible to produce anisotropic and porous or dense particles of a material chosen from zirconium and / or hafnium derivatives, doped or non-doped, preferably chosen from doped or non-doped sulphated zirconium and / or hafnium derivatives, phosphated zirconium and / or hafnium derivatives doped or otherwise, doped zirconium and / or hafnium carbonate derivatives or not, preferably chosen from the basic sulphate of zirconium and / or hafnium doped or not, the basic phosphate of zirconium and / or hafnium doped or not, the basic carbonate of zirconium and / or hafnium doped or no, and mixtures of such particles. Step d) makes it possible to manufacture anisotropic and porous particles made of a material chosen from zirconium and / or hafnium hydrates, doped or otherwise. Such anisotropic and porous particles are not known to the inventors. In particular embodiments of the invention, the method may still have one or more of the following features. - The polar solvent is water. The first reagent is chosen from the solvent-soluble zirconium and / or hafnium salts, the zirconium and / or hafnium alkoxides, the acid-soluble zirconium and / or hafnium derivatives in the solvent, preferably selected from zirconium and / or hafnium oxychlorides, oxides of zirconium and / or hafnium, preferably selected from zirconium and / or hafnium oxychlorides, and mixtures thereof. - The concentration of Zr4- and / or Hf t ions provided by the first reagent in the mother liquor is between 0.01 and 3 mol / liter. This concentration may be greater than 0.1 mol / liter and / or be less than 1.2 mol / liter. The second reagent chosen to provide SO42- and / or PO43. The concentration of the additive in the mother liquor is between 10 mole / liter and 1 mole / liter. The concentration of the additive may be greater than 10 -3 mol / liter and / or be less than 10 mol / liter. The mother liquor is such that: the acidity is between 0.6 and 2 mol / l; and the concentration of Zr4- and / or Hf + in the mother liquor is between 0.1 and 1.2 mol / l; and the molar ratio of anionic groups / (Zr 'and / or H14 +) is between 0.3 and 1, in particular between 0.6 and 1; and the concentration of additive in the mother liquor is between 10 and 10-1 mol / l; and in step b), the heating ramp is between 10.2 and 1 ° C / minute; and the heating temperature, i.e. the temperature at the bearing, is between 55 ° C and 80 ° C, in particular between 55 ° C and 70 ° C; and the duration of maintenance at the stage is between 15 minutes and 2 hours. Preferably, the mother liquor is adapted so as to lead to a powder comprising more than 20%, more than 50%, more than 80%, more than 90%, or even more than 95% by number of particles in derivatives of zirconium and / or hafnium, optionally doped, at the end of step b) or step c), zirconium hydrates and / or hafnium, optionally doped, at the end of d), or optionally zirconium and / or hafnium oxides, at the end of step e). The mother liquor is such that: the acidity is between 1.6 and 3 mol / l; and the concentration of Zr4 and / or Hf + in the mother liquor is between 0.1 and 1.2 mol / l; and the molar ratio of anionic groups / (Zr4 + and / or Hf4-) is between 0.5 and 1, in particular between 0.5 and 0.8; and the concentration of additive in the mother liquor is between 10 'and 10-2 mol / i; and in step b), the heating ramp is between 10 2 and 1 ° C / minute; and the heating temperature is 60 to 80 ° C; and the duration of maintenance at the stage is between 1 hour and 10 hours. The mother liquor is such that: the acidity is between 1.2 and 3 mol / l; and the concentration of Zr4- and / or Hf4 + in the mother liquor is between 0.1 and 1.2 mol / l; and the molar ratio of anionic groups / (Zr`` and / or Hf'-) is from 0.8 to 2.0; and the concentration of additive in the mother liquor is between 10-3 and 10-1 mol / l; and in step b), the heating ramp is between 10-2 and 1''C / minute; and the heating temperature is between 60 ° C. and 80 ° C. and the residence time is between 30 minutes and 2 hours.The mother liquor is such that: the acidity is between 1, 2 and 3 mol / l and the concentration of Zr4 + and / or Hf in the mother liquor is between 0.1 and 1.2 mol / l and the molar ratio of anionic groups / (Zr4- and / or Hf4-) is between 0.3 and 1, and the additive concentration in the mother liquor is between 10 and 10-2 mol / l, and in step b) the heating ramp is between 10 and 10-2 mol / l; 2 and 1 ° C / min, and the heating temperature is between 55 ° C and 80 ° C and the hold time is between 30 minutes and 2 hours - The mother liquor is such that: acidity is between 1.2 and 3 mol / l, and the concentration of Zr4 + and / or Hf4 + in the mother liquor is between 0.1 and 1.2 moUl, and the molar ratio of anionic groups / (Zr4- and / or or HÉ-) is between 0, 3 and 1, and the concentration of additive in the mother liquor is between 10.3 and 10-mol / l; and in step b), the heating ramp is between 10.2 and 1 ° C / minute; and the temperature of the bearing and between 60 ° C and 80 ° C; and the dwell time is between 1 hour and 5 hours. The mother liquor is such that: the acidity is between 0.6 and 3 mol / l; and the concentration of Zr4- and / or Hf1- in the mother liquor is between 0.1 and 1.2 mol / l; and the molar ratio of anionic groups / (Zr '' and / or Hfi-) is between 0.5 and 2; and the concentration of additive in the mother liquor is between 10 'and 1 mol / l; and in step b), the heating ramp is between 10.2 and 10 ° C / minute; and the heating temperature is 60 ° C to 100 ° C; and the duration of the maintenance at the landing is between 30 minutes and 5 hours.

According to a second main embodiment, the invention relates to a process for producing a powder of particles of zirconium hydrates and / or hafnium doped or not and mixtures thereof, comprising a step of basic hydrolysis of a powder of starting particles of a zirconium derivative and / or hafnium doped or not, preferably selected from sulfated derivatives of zirconium and / or hafnium doped or not, phosphatic derivatives of zirconium and / or hafnium doped or not, carbonated derivatives of zirconium and / or hafnium doped or not, preferably selected from basic sulfate zirconium and / or hafnium doped or not, basic phosphate zirconium and / or hafnium doped or not, the basic carbonate of zirconium and / or hafnium doped or not, and mixtures thereof, or a starting powder in a mixture of such particles, said starting particles consisting of anisotropic base particles, aggregated or not. The hydrolysis step may in particular be a step d) and, in particular, comprise one or more of the optional characteristics relating to step e). The starting particle powder may in particular be a powder manufactured according to a manufacturing method according to the first main embodiment described above, and in particular be a powder obtained at the end of step b) or from step c).

According to a third main embodiment, the invention relates to a method for manufacturing a powder (doped or non-doped zirconium oxide and / or hafnium oxide particles, preferably ZrO 2, doped ZrO 2, doped HfO 2, HfO 2 , comprising a step of calcination of a powder of starting particles of a material chosen from doped or non-doped zirconium and / or hafnium derivatives, zirconium hydrates and / or hafnium doped or not, and mixtures thereof , preferably chosen from sulphated zirconium and / or hafnium derivatives doped or not, phosphated derivatives of zirconium and / or hafnium doped or non-doped, carbonated derivatives of zirconium and / or hafnium doped or not, doped or non-doped hafnium and zirconium hydrates, and mixtures thereof, preferably chosen from zirconium and / or doped hafnium basic sulphate, basic zirconium phosphate and / or doped hafnium or no, basic zirconium carbonate and / or doped hafnium or not, doped or non-doped zirconium and / or hafnium hydrates, and mixtures thereof, or a powder comprising a mixture of such starting particles, said starting particles being constituted by anisotropic base particles, aggregated or otherwise and, when in a hydrate, the starting particles being further porous. The calcination step may be a step el) of the first main embodiment and include one or more of the optional features of this step. The anisotropic starting particles may in particular be particles manufactured according to a process according to the first main embodiment, and in particular be derived from steps b), c) or d).

According to a fourth main embodiment, the invention also relates to a process for manufacturing a powder of particles of zirconium oxides and / or hafnium doped or not and their mixtures, comprising a hydrothermal treatment stage of a powder of starting particles of a material chosen from doped or non-doped zirconium and / or hafnium derivatives, doped or non-doped hafnium and zirconium hydrates and mixtures thereof, preferably chosen from sulphated zirconium derivatives and and / or hafnium doped or not, phosphated derivatives of zirconium and / or hafnium doped or not, doped or non-doped carbonated derivatives of zirconium and / or hafnium, doped zirconium and / or hafnium hydrates or not and mixtures thereof, preferably chosen from basic sulfate of zirconium and / or hafnium doped or not, the basic phosphate of zirconium and / or hafnium doped or not, the basic carbonate of zirconium and / or doped hafnium or not, hydrates d zirconium and / or hafnium doped or not and mixtures thereof, or a mixture of these particles, said starting particles consisting of anisotropic base particles, aggregated or not, and, when they are in a hydrate, the starting particles being furthermore porous.

The hydrothermal treatment step may, in particular, be a step e2) like that of a method according to the first main embodiment and comprising one or more optional characteristic (s) of step e2) of the first main embodiment. The starting particles may be manufactured according to a method according to the first main embodiment, and in particular be derived from steps b), c) or d).

Products The processes described above made it possible to discover several new particles. Steps a), b) and c) have led to the discovery of anisotropic base particles in a material chosen from doped or non-doped zirconium and / or hafnium derivatives, preferably chosen from sulphated zirconium derivatives and / or or doped or non-doped hafnium, phosphated derivatives of zirconium and / or hafnium doped or not, carbonated derivatives of zirconium and / or hafnium doped or not and mixtures thereof, preferably selected from basic zirconium sulfate and / or doped hafnium or not, the basic phosphate of zirconium and / or hafnium doped or not, the basic carbonate of zirconium and / or hafnium doped or not and mixtures thereof. The invention thus also relates to a powder comprising more than 20%, more than 50%, more than 80%, more than 90%, or even more than 95% by number of anisotropic base particles, aggregated or not, in a chosen material. from doped or non-doped zirconium and / or hafnium derivatives, preferably chosen from doped or non-doped sulphated zirconium and / or hafnium derivatives, phosphated derivatives of zirconium and / or hafnium doped or non-doped, carbonated derivatives of zirconium and / or hafnium, doped or not, and mixtures thereof, preferably chosen from basic sulfate of zirconium and / or hafnium doped or not, basic phosphate of zirconium and / or hafnium, doped or otherwise , the basic carbonate of zirconium and / or hafnium doped or not and mixtures thereof, or a mixture of these particles. In a preferred embodiment, these particles are dense. In another embodiment, especially when adding a pore-forming agent in step a), these particles are porous.

These base particles are insoluble in water and, preferably, hydrolyzable. Preferably, the material of these base particles is amorphous when not doped. When this material is doped, however, it may present crystals formed from the dopant. In other words, on an X-ray diffraction diagram, the peaks corresponding to the detection of crystals substantially all correspond to crystals containing a dopant.

Steps a), b), optionally c), and d), have led to the discovery of anisotropic and porous base particles, aggregated or not, in a material chosen from zirconium hydrates and / or hafnium, doped or not, and their mixtures. The invention therefore also relates to a powder comprising, for more than 20%, more than 50%, more than 80%, more than 90%, or even more than 95% by number, anisotropic and porous base particles, aggregated or not , into a zirconium hydrate and / or hafnium, doped or not, or a mixture of such hydrates. The base particles may have identical or different chemical compositions. Preferably, the material of these particles is amorphous when it is not doped. When this material is doped, however, it may present crystals formed from the dopant.

Steps a), b), optionally c), d) and el) (calcination) and steps a), b), optionally c), d) and e2) (hydrothermal treatment) have led to the discovery of particles of base, anisotropic and porous, aggregated or not, of a material chosen from doped or non-doped zirconium and / or hafnium oxides and their mixtures, preferably ZrO 2, doped ZrO 2, HfO 2, doped HfO 2.

The invention thus also relates to a powder comprising more than 20%, more than 50%, more than 80%, more than 90%, or even more than 95% by number of base particles, anisotropic and porous, aggregated or not, in a material selected from oxides of zirconium and / or hafnium doped or not and mixtures thereof, or a mixture of these particles. Preferably, the material of these particles is crystallized.

The invention also relates to a powder comprising more than 20%, more than 50%, more than 80%, more than 90% or even more than 95% by number of basic particles, anisotropic and dense, aggregated or not, in one material chosen from zirconium and / or hafnium oxides, doped zirconium and / or hafnium oxides and mixtures thereof, the dopant being: an oxide of an element chosen from yttrium Y, lanthanum La, cerium Ce, scandium Sc, calcium Ca, magnesium Mg and mixtures thereof, said dopant being preferably in solid solution with zirconium oxide and / or hafnium oxide, preferably in a quantity molar less than or equal to 20%. The product according to the invention may in particular be a zirconia doped with yttrium oxide or a zirconia doped with cerium oxide; an aluminum oxide A1, preferably dispersed in zirconium and / or hafnium oxide, preferably in a molar amount of less than or equal to 20%, more preferably less than or equal to 3%; - and their mixtures. Preferably, the base particles of said powder are in the form of platelets and / or needles and / or are aggregated in the form of stars and / or lamellae and / or sea urchins and / or hollow spheres. More preferably, the base particles are in the form of platelets and / or are aggregated in the form of lamellae and / or stars, sea urchins and / or hollow spheres. Preferably, the material of these particles is crystallized.

According to one particular embodiment, the invention relates to a particle powder having a maximum size of less than 200 m, and comprising more than 20%, more than 50%, more than 80%, more than 90%, or even more than 95%. % by number of anisotropic base particles, aggregated or not, and selected from the group consisting of: dense or porous base particles of a zirconium and / or hafnium derivative, doped or undoped, insoluble in water and which is hydrolyzable, amorphous or containing only crystals which include a dopant, said zirconium derivative being able to be chosen in particular from basic zirconium and / or hafnium sulphate, basic zirconium and / or hafnium phosphate, basic zirconium and / or hafnium carbonate and mixtures thereof; - Porous base particles of zirconium e: / or hafnium hydrates, doped or undoped, amorphous or containing only crystals as crystals including a dopant; - Porous base particles ZrO2 zirconia and / or hafnium oxide HfO2, doped or undoped, - and the mixtures of these basic particles. Preferably, in particular for the porous base particles of hydrates of zirconium and / or hafnium, doped or undoped, amorphous or containing, for only crystals, only crystals including a dopant and for the porous base particles of zirconia ZrO2 and / or hafnium oxide HfO2, doped or undoped, said powder has a porosity index Ip greater than 2, preferably greater than 5, preferably greater than 10, or even greater than 20, or even In general, the invention relates to a powder obtained or obtainable according to a process according to the invention, in particular by a process comprising a step e1) of calcination at a temperature below 1200 ° C.

A powder according to the invention may also comprise one or more of the following optional characteristics: the maximum size (D99.5) of the particles of the powder (basic or aggregated) is less than 150 m, less than 100 m, less than 80 m, or less than 50 m. - The particles are insoluble in water. - More than 20%, more than 50%, more than 80%, more than 90%, or even more than 95%, or even substantially 100% by number of the basic particles, independent or constituting an aggregated particle, have a form chosen from a wafer, in particular a wafer with a thickness greater than 50 nm and / or a needle, in particular a needle with a length greater than 200 nm. At least 80%, preferably at least 90% or even substantially 100% by number of said particles are ordered aggregated particles, in particular in a lamellar form, in particular consisting of 2 to 50 platelets. star-shaped, in particular having 3 to 15 branches, preferably having more than 3, 4 or 5 branches, and in sphere, in particular in a hollow sphere, preferably having a sphericity index greater than 0.7, and / or are aggregated disordered particles, especially in the form of sea urchins. The aggregated particles may in particular result from an assembly of base particles into a needle or wafer. These base particles can themselves be assembled in the form of intermediate aggregated particles: For example, the aggregated particles may consist of an assemblage of stars or an assembly of stars and needles. Aggregated particles consist of base particles of all sizes greater than 250 nm. All dimensions of the basic or aggregated particles are greater than 50 nm, greater than 100 nm, greater than 200 nm, greater than 250 nm, and even greater than 500 nm. A size greater than 50 nm is particularly advantageous for creating pores allowing a good diffusion of gases, and therefore to achieve good catalytic or filtration performance. The particles may be anisotropic, in particular having a wafer shape or having a needle shape, in particular of a length greater than 200 nm. At least 95% by number of the base particles have a shape such that all its dimensions are greater than 50 nm. The particles are doped and the dopant of the particles is chosen from the compounds of an element chosen from yttrium Y, scandium Sc, cerium Ce, silicon Si, sulfur S, aluminum Al, calcium Ca magnesium Mg and mixtures thereof. If the particles are zirconia and / or hafnium oxide particles, the doping compound may in particular be an oxide of an element selected from Y, La, Ce, Sc, Ca, Mg and mixtures thereof. in solid solution with zirconium oxide and / or hafnium oxide, preferably in a molar amount of less than or equal to 20%. In particular, the invention relates to a zirconia powder doped with yttrium oxide or a zirconia doped with cerium oxide; an oxide of an element chosen from Si, Al, S and their mixtures dispersed in zirconium oxide and / or hafnium oxide. When the oxide is an aluminum oxide, preferably its molar amount is less than or equal to 20%, more preferably less than or equal to 3%; If the particles are zirconium and / or hafnium hydrate particles, the doping compound may in particular be a hydrate of an element selected from Y, La, Ce, Sc , Ca, Mg and mixtures thereof, in intimate molecular mixture with zirconium hydrate and / or hafnium, preferably in a molar amount less than or equal to 20%. The invention relates in particular to a powder of a mixed hydrate of zirconium and yttrium, and / or a mixed hydrate of zirconium and cerium; an aluminum hydrate dispersed in zirconium hydrate and / or hafnium, preferably in a molar amount of less than or equal to 20%, more preferably less than or equal to 3%; an oxide of an element chosen from Si, S and their mixtures, dispersed in zirconium and / or hafnium hydrate. If the particles are particles of a zirconium and / or hafnium derivative, the doping compound may in particular be a derivative of an element chosen from Y, La, Ce, Sc, in intimate molecular mixture with the derivative. zirconium and / or hafnium, preferably in a molar amount of less than or equal to 20%. The invention particularly relates to a powder of a mixed derivative of zirconium and yttrium or a mixed derivative of zirconium and cerium; a salt of an element selected from Ca, Mg and mixtures thereof, in an intimate molecular mixture with the zirconium and / or hafnium derivative, preferably in a molar amount of less than or equal to 20%; an aluminum hydrate, in an intimate molecular mixture with the zirconium and / or hafnium derivative or located on the surface of the zirconium and / or hafnium derivative, preferably in a molar amount of less than or equal to 20%, of still preferably less than or equal to 3%; an oxide of an element selected from Si, S and mixtures thereof, in intimate molecular mixture with the zirconium and / or hafnium derivative or located on the surface of the zirconium and / or hafnium derivative. Preferably, the molar amount of dopant is determined to be less than 40% or even less than 20% or even less than 10% or even less than 5% or even less than 3% of the mass of the particulate material. . - The particle powder has a specific surface area preferably greater than 10 m 2 / g, or even greater than 20 m 2 / g, or even greater than 50 m 2 / g, or even greater than 100 m 2 / g. The sum of the mesoporous and microporous volumes of the powder is preferably greater than 0.05 cm 3 / g, or even greater than 0.1 cm 3 / g, or even greater than 0.15 cm 3 / g. - Whatever the embodiment, preferably, the impurity content of a powder according to the invention is less than 0.7%, preferably less than 0.5%, preferably less than 0.3%, more preferably less than 0.1%, in percentages by mass of dry matter. The invention also relates to a powder having a maximum particle size (D99.5) of less than 200 m and having a porosity index Ip of less than 2, the porosity index being equal to the Asr / Asg ratio where Asg is theoretical geometrical surface area calculated from the shape and particle size determination of the powder; Asr is the measurement of the actual specific area by BET; said powder having more than 20% by number of base particles - having a sphericity index of less than 0.6, - aggregated in the form of stars having 3 to 15 branches or slats consisting of 2 to 50 platelets, and - consisting of a zirconium and / or hafnium oxide of formula MON, M being Zr4-, Hf-, or a mixture of Zr4- and Hf-, and x being a non-zero positive number. Insofar as they are not incompatible with this embodiment, the characteristics of a powder according to the previously described embodiment are applicable to this powder.

The invention also relates to a powder having a maximum particle size (D99.5) of less than 200 m and having a porosity index Ip of less than 2, the porosity index being equal to the Asr / Asg ratio where - Asg is theoretical geometrical surface area calculated from the shape and particle size determination of the powder; Asr is the measurement of the specific surface area by BET, said powder comprising more than 20% by number of base particles having a sphericity index of less than 0.6, and consisting of an oxide of zirconium and / or hafnium of MON formula, M being Zr4-, Hf 4-, or a mixture of Zr4 `and Hf +, and x being a non-zero positive number, said oxide, said first oxide, being doped by means of a dopant chosen from: a second oxide of an element selected from Y, La, Ce, Sc, Ca, Mg and mixtures thereof in solid solution with said first oxide; a second oxide of an element chosen from Si, Al, S and their mixtures dispersed in said first oxide; - and their mixtures. Insofar as they are not incompatible with this embodiment, the characteristics of a powder according to the previously described embodiments are applicable to this powder. Preferably, said base particles have a wafer shape and / or are aggregated in the form of stars and / or lamellae and / or sea urchins and / or hollow spheres.

The invention also relates to a structural body, in particular manufactured by extrusion techniques, granulation (for example by atomization), injection molding, pressing (unidirectional pressing, hot pressing, CIP, HIP ...), pouring (slip casting, strip casting, etc.), coating (by centrifugation or spin coating, dipping or dip coating, etc.) chosen from a substance having a density greater than 98% of the theoretical density of the material constituting it, a body having a porosity index Ip> 2, a layer of thickness less than 1 mm having a porosity index Ip> 2 or a density greater than 98% of the theoretical density of the component material, in particular a catalytic coating or washcoat in English, for example, obtained by dip coating or by spin coating or by strip casting, said body or said layer being obtained from a powder according to the invention.

The invention also relates to the use of a powder according to the invention or of a body according to the invention as a catalyst, as a support for a catalyst, as a filter element, in particular for the treatment of gases or liquids, as part of a fuel cell, in particular an anode or an electrolyte, in particular a SOFC type fuel cell, as a piezoelectric material, as an optical connector, as a dental ceramic or, more generally, as a structural ceramic, that is to say in any application where good mechanical properties and / or good resistance to wear are sought.

The invention also relates to a catalyst, a support for a catalyst, a filter element, in particular for the treatment of gases or liquids, an element of a fuel cell, in particular an anode or an electrolyte, in particular a fuel cell of the SOFC type, a piezoelectric material, an optical connector, a dental ceramic or, more generally, a structural ceramic, that is to say a part having good mechanical properties and / or a good one; wear resistance, remarkable in that it comprises or is obtained (e) from a powder according to the invention.

BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent on reading the detailed description which follows and on examining the appended drawing in which FIG. 1 represents a diagram describing the main steps of a process. according to the invention; Figures 2a to 2e show needle, wafer, lamella, star and hollow sphere particle patterns, respectively; Figures 3a to 3e show photographs of particle powders. 18 Definitions Percentiles or percentiles 0.5 (D0 5), 50 (D50), and 99.5 (D99.5) are the particle sizes of a powder corresponding to percentages by weight, 0.5% of 50 % and 99.5%, respectively, on the cumulative size distribution curve of the particle sizes of the powder, the particle sizes being ranked in ascending order. For example, 99.5% by weight of the powder particles have a mesh size below D99.5 and 0.5% of the bulk particles are larger than D9.5. 0.5% by weight of the particles of the powder have a size less than D0.5. Percentiles can be determined using a particle size distribution using a sedigraph. The sedigraph used here is a Sedigraph 5100 from Micromeritics. D50 corresponds to the median size of a set of particles, that is to say to the size dividing the particles of this set into first and second populations equal in mass, these first and second populations containing only particles presenting a upper, or lower respectively, at the median size. The maximum particle size of a powder is the 99.5 percentile (D99.5) of said powder. A powder is a set of particles. These particles can be basic, that is to say, not associated with other basic particles, agglomerated or aggregated. Unlike a simple agglomerate of base particles, an aggregated particle, also called aggregate, does not dissociate easily and resists, for example, in the case of ultrasound application. Conventionally, the bonds between base particles in an aggregated particle are chemical bonds while in an agglomerate, they result from effects of charge or polarity.

In the present description, the term "particles" is defined as the base particles and the aggregates. By impurities is meant the inevitable constituents, necessarily introduced with the raw materials or resulting from reactions with these constituents. Here, by impurities, is meant any element different from the zirconium compound and / or hafnium (derivative, hydrate or oxide), and optional dopant (s). The impurity content of a hydrate or a derivative is measured after calcination at 1000 ° C. In the case of a derivative, the element (s) of the anionic group (s) of said derivative are not considered as impurities. For example, after calcination at 1000 ° C of a ZBS, the residual sulfur is not considered an impurity. The term "doping agent" or "doping compound" is a minor component of the product, that is to say which does not constitute the constituent having the highest molar content in the material under consideration. For example, an alumina doped zirconia contains a molar amount of alumina less than or equal to that of zirconia. By extension, the species introduced during the manufacturing process of the doped product is also called dopant. The latter dopant may be identical to the dopant present in the doped product, or be different, that is to say constitute a precursor of the dopant present in the doped product. The dopant present in the doped product can then also be described as a "successor" of the dopant introduced during the manufacture of the doped product. For example, the addition of YC13 can lead to a basic zirconium sulfate doped with yttrium basic sulfate. The dopant of a particle can be localized: within the particle in the form of a defined compound (for example ZrOSO4, ZrCeO4) or a solid solution or a molecular intimate mixture (by example (Zr, Y>) BS, (ZrXCey) O2, with x + y = 1) and / or o of a dispersion (for example dispersion of alumina in a zirconia particle) and / or o of inclusions and or on the surface of the particle. A compound of the form M (OH) X (N ') y (OH 2) z is generally derived, M being a metal cation or a mixture of metal cations and N' an anion or a mixture of anions, the indices x and y being strictly positive numbers, the index z being a positive or zero number, and having a solubility in water at a temperature below 20 ° C of less than 10-3 mol / l. The anions can be as well inorganic (CF) as organic (acetate CH3-COO-), monoatomic (F) or polyalomic (SO42). Especially if M is Zr4, Hf i-. or a mixture of Zr4` and Hf -, the derivative will be referred to as zirconium derivative, hafnium derivative or zirconium and hafnium derivative, respectively.

Steps b) and c) in particular make it possible to manufacture zirconium and / or hafnium derivatives. Unless otherwise indicated, in the present description and claims, a derivative is a derivative capable of being manufactured by a process according to the invention.

Zirconium basic sulphate or ZBS is a zirconium derivative of general formula Zr (OH) x (SO4) y (H2O), with y between 0.2 and 2, x such that x + 2y = 4, and z a positive or zero number. Basic zirconium carbonate or ZBC is a zirconium derivative of the general formula Zr (OH) x (CO 3) y (H 2 O) z, with y between 0.2 and 2, x such that x + 2y = 4, and z a positive number or zero. Basic zirconium phosphate is a zirconium derivative of general formula Zr (OH) x (PO 4) y (H 2 O) Z, with y being between 0.2 and 2, x such that x + 3y = 4, z is a positive number. or none. A compound of the form M (OH) x (N ') y (OH 2) z is called salt, M being a metal cation or a mixture of metal cations and N' an anion or a mixture of anions, the indices x, y and z being positive or zero numbers, x + y> 0, and having a solubility in water at a temperature below 20 ° C of greater than 10-3 mol / l. The anions can be as well inorganic (Cr) as organic (acetate CH3-COO-), monoatomic (F-) as well as polyatomic (SO42). In the case of zirconium, typical salts are zirconium oxychloride Zr (OH) 2 Cl 2 (OH 2) 4, zirconium chloride ZrCl 4 and zirconium sulfate Zr (SO 4) 2. Zirconium oxychloride or ZOC is the crystallized zirconium salt of formula Zr (OH) 2 Cl 2 (OH 2) 4. A compound of the MOx (OH) y (OH 2) z form is conventionally hydrated, M being a metal cation or a mixture of metal cations, the indices x and z being positive or zero numbers, the index y being a number positive, and 2x + y being equal to the valency of the cation or equal to the average valency of the cation mixture. For example, zirconium hydrates, or ZHO, have the formula ZrOx (OH) y (OH2) z, where z> 0, y> 0 and 2x + y = 4.

In particular, if M is Zr4-, Hf 4-, or a mixture of Zr4 + and Hf, the hydrate will be a zirconium hydrate, hafnium hydrate, or zirconium hydrate and hafnium hydrate, respectively.

Unless otherwise stated, in the present description and claims, a hydrate is a hydrate capable of being made by a process according to the invention. A compound of formula MOX is conventionally called oxide, where M is a metal cation or a mixture of metal cations, and x is a non-zero positive number. For example, ZrO 2 zirconia is a zirconium oxide. In the particular case of sulfur and phosphorus, the compounds in the oxide form also include all oxidized compounds of sulfur and phosphorus respectively. An oxidized sulfur compound is for example 5042, an oxidized phosphorus compound is for example PO43-.

In the absence of contrary indications, in the present description and claims, an oxide is an oxide capable of being manufactured by a process according to the invention. Oxoanion is conventionally referred to as an oxide-containing anion, of the form QOx Q being a metal (for example silicon) or a non-metal (for example carbon, phosphorus, sulfur), n being a whole number greater than or equal to at 1 and x being equal to (n + w) / 2, with w the valence of the metal or non metal considered. A thermal treatment is called calcination which makes it possible to transform a product into an oxide form. Typically the calcination is carried out at a temperature of 500 ° C and more. Drying is a heat treatment, generally carried out at a temperature below 400 ° C., which makes it possible to eliminate all the solvent, or even only the solvent that does not participate in the constitution of the dried product. For example, in the case where the solvent is water, the drying of a zirconium hydrate will eliminate water not being the water of constitution of said hydrate. Unlike calcination, drying does not lead to transformation of the treated product into an oxide form.

Open porosity is the porosity attributable to all accessible pores of a material in the form of a powder or a shaped solid. According to the classification of the International Union of Pure and Applied Chemistry, 1994, vol.66, n ° 8, pp.1739-1758, the accessible pores are divided into 3 categories according to their equivalent diameter: macropores are accessible pores having an equivalent diameter greater than 50 nm; mesopores are accessible pores having an equivalent diameter of between 2 and 50 nm; micropores are accessible pores having an equivalent diameter of less than 2 nm; the equivalent diameter of a pore being defined by the smaller dimension of said pore, as indicated in the IUPAC document. For example, if the pore is cylindrical, the equivalent diameter will be the diameter of the cylinder. Open porosity is the sum of macroporosity, mesoporosity and microporosity.

In each of these categories, classically called porous volume, the volume occupied by the accessible pores of the particles relative to the mass of the powder or body considered. The macroporous volume, the mesoporous volume and the microporous volume are the volumes relative to the mass of powder or solid corresponding to macropores, mesopores and micropores, respectively.

The macroporous volume is conventionally measured by mercury porosimetry; the mesoporous volume and the microporous volume are conventionally measured by adsorption and desorption of nitrogen at -196 ° C. A blowing agent is an agent which, introduced in step a) in the mother liquor, leads to the creation of pores, mostly open, in the particles.

The porosity index Ip of a particle powder or a body is referred to as the Asr / Asg ratio where - Asg is the theoretical geometrical specific area calculated from the shape and size determination of the particles of the powder. or body; Asr is the measurement of the actual specific area by BET. Thus, if Ip = 1, ie Asr = Asg, the particles of the powder or of the body do not have open porosity and are perfectly dense. In practice, if Ip> 2, ie Asr> 2Asg, the particles of the powder or of the body have a significant open porosity, and are here described as porous particles; O if IF <2, the particles of the powder or of the body are very slightly porous and are here described as dense particles.

The porosity index characterizes the open porosity of the particles of the powder or the body (microporosity, mesoporosity and macroporosity). A porous aggregate, a porous agglomerate or a porous solid body, is an aggregate, agglomerate or solid body, respectively, having a porosity index Ip> 2. When two compounds and their mixtures are mentioned, not only these two compounds, but also mixtures of these compounds in which the grains of the compounds are clearly distinct, but also the solid solutions and / or intimate molecular mixtures of these compounds. The mixtures of the zirconium compounds and the hafnium compounds include, for example, a solid solution of zirconium and hafnium (Zr, Hf) O2 and a mixture of ZrO2 grains and HfO2 grains.

The acidity of a solution or suspension is equal to the concentration of H, ion, of said solution or suspension. The acidity of a solution or suspension is also equal to 10-pH. The acidity is expressed in mol / l. The term "textural properties" collects all the physical surface properties characterizing a powder or a solid body shaped, namely the specific surface area, the mesoporous volume, the microporous volume, the macroporous volume, the size distribution of the particles. pores and average pore size. Basic particles are called "elementary" particles, and in particular needle-shaped or wafer-shaped particles: A needle is called an anisotropic particle of generally elongate shape, that is to say extending mainly along the a guideline, rectilinear or not. However, the length L, measured along this guideline, is less than 50 times the width "1", the width "1" being the largest dimension that can be measured in the set of transverse planes (perpendicular to the guideline) along the guideline. In addition, the thickness "e", i.e., the smallest dimension measured in the transverse plane in which the width "1" is measured, is greater than 0.5 times the width "1". A needle is shown schematically in Figure 2a. Figures 3b and 3c are photographs of needle powder.

The cross sections of a needle, that is to say perpendicular to the direction of the line decreasing its length, may be arbitrary, and in particular be polygonal or have the shape of an ellipse or a circle. According to the invention, preferably 1.67 <L / 1 <50, preferably 2 <L / 1, more preferably 5 <L / 1. Preferably always, L / 1 <20, and preferably L / 1 <10. A wafer is called a particle having a generally broad and shallow shape, in the manner of a straw. In other words, a plate has two large faces, generally substantially parallel to one another, spaced apart from each other by a small distance from the dimensions of said faces. A wafer is shown schematically in Figure 2b. Figure 3f is a photograph showing platelets (mixed with cluster particles). More specifically, it is considered that a particle is a wafer if the length "L", corresponding to the largest dimension measurable on one of the two large faces of the particle, is less than 1.5 times the width "1", the width "1" being the largest dimension that can be measured in the set of transverse planes (perpendicular to the length) along the direction of the length, and if the thickness "e" is i.e., the smallest dimension measured in the transverse plane in which the width "1" is measured, is less than 0.5 times the width "1". According to the invention, if e, L, and 1 respectively denote the thickness, the length, and the width of a wafer, preferably e 0.25. 1, preferably e 0.22. 1 and / or L 1.2. 1. Preferably according to the invention, the sections perpendicular to the direction of the thickness are substantially constant over the entire thickness of the wafer. More preferably, according to the invention, the sections perpendicular to the direction of the thickness have more than 7 sides, or have the general shape of an ellipse or a circle. Among the aggregates, one distinguishes the "ordered" forms and the "disordered" forms, according to whether the basic particles are arranged so as to constitute an aggregate of definite general shape or not, respectively. Among the ordered forms, lamellas, stars and spheres, in particular hollow spheres, are particularly distinguished.

A flake consists of a flat stack of at least two platelets of similar size, preferably with a high recovery rate. In other words, the plates are similar, in contact with their large faces and, preferably, well superimposed on each other. A coverslip is shown schematically in Figure 2c. Preferably, a lamella in the sense of the present description and claims is such that W1 '/ W1 <1.5 and W2' / W2 <1.5, W1 and W2 designating the major axis and the minor axis, respectively, of the smallest ellipse through which each of the platelets constituting the lamella can pass, in the direction of its thickness (that is to say flat), and W 1 'and W2' designating the major axis and the minor axis, respectively, of the smaller ellipse through which the slat can pass, following the stacking direction. Preferably according to the invention, the lamellae comprise less than 50, preferably less than 20 platelets. Still preferably, according to the invention, W 1 '/ W 1 <1.2 and W 2', 'W 2 <1.2, more preferably W 1' / W 1 <1.1 and W 2 '/ W 2 <1.1, W 1 , W2, W1 'and W2' being as defined above. A star is a particle consisting of an assembly of at least two needles according to the invention, possibly of different dimensions, needles intersecting substantially in the center of the star. A star is shown schematically in Figure 2d. The aggregation of the needles to form stars is visible in the photograph of Figure 3d. A length L of a star is called the length of the major axis of the smallest ellipse in which the star can be inscribed (see Figure 2d). Preferably, the number of needles constituting a star is less than 15, preferably less than 8.

A sea urchin is a particle consisting of an assembly in disordered form of base particles, including needles and / or platelets according to the invention. Sea urchins are therefore patatoids of indeterminate shape, in the sense that the general shape of a sea urchin can be very different from that of another sea urchin. The aggregation of needles and stars to form sea urchins is visible in the photograph of Figure 3e.

A hollow sphere is an isotropic particle having a central cavity such that if D denotes the largest outside diameter of the particle (its largest outside dimension) and D 'is the largest inside diameter of the cavity (its largest inside dimension). ), D / D '<2. A hollow sphere is shown schematically, in section, in Figure 2e. An aggregation of needles to form hollow spheres is visible in one of the photographs of Figure 3g. A hollow sphere according to the invention is preferably made of needles.

Preferably, according to the invention, the sphericity index of a hollow sphere is greater than 0.7, more preferably greater than 0.8. The term sphericity index is the ratio between the smallest dimension and the largest dimension of a particle, the dimensions being measured "overall" along axes passing through the barycenter of the particle.

A particle is said to be isotropic if its sphericity index is greater than 0.6. A particle is called anisotropic If its sphericity index is between 0.02 and 0.6. For example, 0.02 is the sphericity index of a needle whose length L is 50 times greater than the thickness e. The sphericity index may be greater than 0.05 (length-to-thickness ratio equal to 20), or even greater than 0.1 (L / e ratio of 10). The sphericity index may be less than 0.5, or even less than 0.4, or even less than 0.35, or even less than 0.3. Characterization methods Particle morphology, except for hollow spheres The presence of particles with particular morphologies is generally possible by observation of scanning electron micrographs like those in the figures. These pictures also make it possible to evaluate the dimensions of the particles. In particular, when the particles of the observed powder appear to have substantially all the same morphology, it is possible to determine the average dimensions of all of these particles. Morphology of the hollow spheres After resin coating and fine polishing (micron diamond-paste finishing) of a sample to be characterized, plates with between 10 and 50 hollow spheres are produced using a scanning electron microscope. initial magnification (xl000) used being adapted to achieve the number of hollow spheres to be observed. A large number of shots is necessary, generally more than 50. On the one hand the orientation of each hollow sphere being random and on the other hand the polishing allowing a random section of each hollow sphere, it is then possible to determine the internal structure (cavity). From these images, it is also possible to evaluate, on average on a set of particles, the largest outside diameter of the cavity D and the largest inside diameter of the cavity D '. Chemical analyzes The determination of Cl- chloride ions is carried out after pyrohydrolysis by ion chromatography.

The contents of carbonate (CO3--) and sulfate (SO42) are determined from the carbon and sulfur contents (respectively converted to CO32 and sulphate SO4 '' -) measured on a carbon Sulfur analyzer model LECO CS-300. For the other elements, if the content of the element is greater than 0.1% by mass, it is determined by X-ray fluorescence spectroscopy; if the content of an element is less than 0.1% by weight, it is determined by ICP (Induction Coupled Plasma) on a Vista AX model (marketed by Varian). Loss on ignition The loss on ignition is determined by measuring the mass loss of the product after calcination of the product at 1000 ° C for 1 hour.

Measurements of the specific surface area and of the mesoporous and microporous volumes The textural properties are determined by physical adsorption / desorption of N2 at -196 ° C. on a Nova 2000 model marketed by Quantachrome. The samples are desorbed beforehand at 250 ° C. for 2 hours for the calcined powders or calcined solid bodies and at 100 ° C. for 2 hours for the non-calcined powders. The specific surface area is calculated by the BET method (Brunauer Emmet Teller) as described in Journal of the American Chemical Society 60 (1938) pages 309 to 316. The mesoporous and microporous volumes as well as the size distribution of the mesopores and micropores are determined by the BJH method [described by EP Barrett, LG Joyner, PH Halenda, J. Am. Chem. Soc., 73 (1951) 373] applied to the desorption branch of the isotherm.

Determination of the geometric specific surface area Asg The geometric specific surface area of the particles of a powder or of a body is determined from observations made by scanning electron microscopy. The geometric specific area Asg is given by the formula (1): 6n P, 2 / A = sg (d + D, (1) with p, the theoretical density of the material (determined by Helium intrusion) of the particle i, di and Di respectively the smallest dimension and the largest dimension of the particle i measured "overall" along axes passing through the barycenter of the particle i, and n being the number of particles measured, with n> 200. In the case of aggregated particles, n refers to the number of aggregated particles, and not to the number of base particles constituting them.Measurement of macroporous volume The macroporous volume as well as the size distribution of macropores are determined by Hg porosimetry on a Por model. osizer 9320 sold by the company Micromeritics. The samples are introduced in the form of powder or shaped solid. The maximum applied pressure of 6000 psi makes it possible to measure the porosity for pore diameters greater than 50 nm. Determination of crystalline structure (DRS: analysis) X-ray powder diffraction patterns were obtained on a BRUKER D5005 diffractometer using copper Ka radiation (1.54060Å). The intensity data are recorded over a range of 3-80 ° with a pitch of 0.02 ° and a counting time of 1 s per step. The crystalline phases are identified by comparison with the standard JCPDS files. The crystal structure can be confirmed by other well known methods such as Raman spectroscopy or, locally at a particle base, by transmission electron microscopy.

Determination of the Particle Size Distribution of the Particles The particle size distribution is determined by sedigraphy on a Sedigraph 5100 model sedigraph sold by the company Micromeritics.

The sample to be characterized is suspended in a solution containing sodium metaphosphate and then dispersed twice for 3 minutes under ulters (power of 70 W). The suspension is then introduced with stirring into the equipment for analysis.

DETAILED DESCRIPTION An embodiment of a method according to the invention comprising steps a) to e) as presented above is now described in detail. Step a) In step a), the polar solvent [1] may be selected from water, alcohols, organic solvents and mixtures thereof. Preferably, the polar solvent is water.

The first reagent [2] is selected to provide Zr4 and / or Hf - ions. Preferably, it is soluble in the solvent of the mother liquor. More preferably, it may be chosen from: zirconium salts and / or hafnium soluble in said solvent, such as for example chlorides, oxychlorides, sulphates, oxynitrates, acetates, formates, citrates; zirconium and / or hafnium alkoxides, such as butoxides and propoxides; acid-soluble zirconium and / or hafnium derivatives in said solvent, such as, for example, basic carbonates, hydroxides; and their mixtures. Preferably, the first reagent is selected from the solvent-soluble zirconium and / or hafnium salts and mixtures thereof, preferably from oxychlorides, oxynitrates and mixtures thereof, more preferably from oxychlorides. The second reagent is selected so as to provide anionic groups so as to form in step b), by precipitation with the Zr4- and / or Hf4- ions provided by the first reagent, a zirconium derivative and / or hydrolyzable hafnium, preferably anisotropic.

The second reagent [3] may be chosen so as to provide the anionic groups 5042- or PO43 and mixtures thereof. For example, the second reagent may be a mixture of Na2SO4 and H2SO4. Preferably, the second reagent is selected so as to provide SO42- anionic groups. With a first reagent supplying Zr4- ions, second reagents bringing SO42- or PO43 anionic groups lead to ZBS (Zirconium basic sulphate) or zirconium basic phosphate, respectively, at the end of step b). . Even in the absence of step c), they can lead to ZHO (zirconium hydrate) or ZHO particles doped at the end of step d) of basic hydrolysis of ZBS, or of basic zirconium phosphate. . They can also lead, in the case of step e1) calcination or e2) hydrothermal treatment of ZHO or ZHO doped or ZBS or ZBS doped or basic phosphate zirconium or basic phosphate doped zirconium, to zirconia or zirconia particles doped. In a particular embodiment, the first reagent makes it possible to provide both Zr4 and / or HÉ- ions and anionic groups. For example, the first reagent may be zirconium sulphate, Zr (SO4) 2, which makes it possible to provide both Zr4- and SO42- anionic groups. The ratio of the concentration of anionic groups to the concentration of Zr4 and / or HÉ- ions is preferably between 0.2 and 5. Preferably, this ratio is greater than 0.3, preferably greater than 0.4. more preferably greater than 0.5 and / or less than 2, preferably less than 1.5, more preferably less than 1.2. For example, the ratio of the concentration of anionic groups 5042- to the concentration of Zr4- ions can be between 0.3 and 2, preferably between 0.4 and 1.5, more preferably between 0.5 and 1.2. The mother liquor must have a pH less than or equal to 7, preferably less than or equal to 6, preferably less than or equal to 4, preferably less than or equal to 2. The pH adjustment of the mother liquor can be carried out in particular by additions of acids and / or organic or inorganic bases. The additive [4] makes it possible to modify the morphology and is chosen from the group of: - anionic surfactants and their mixtures, in particular: o carboxylates (of formula R-CO2-G- with R an aliphatic carbon chain, aromatic or alkylaromatic and G- a monatomic or polyatomic cation and / or a mixture of such cations), preferably chosen from ethoxylated carboxylates, ethoxylated or propoxylated fatty acids, sarcosinates of formula RC (O) N (CH3) CH2COO- their mixtures; sulphates (of formula R-SO 3 -G- with R an aliphatic, aromatic or alkylaromatic carbon chain and G-a monoatomic or polyatomic cation and / or a mixture of such cations), preferably chosen from alkyl sulphates, alkyl ether sulphates or ethoxylated fatty alcohol sulfates, nonylphenyl ether sulfates, and mixtures thereof; sulphonates (of formula R-OSO 3 -G- with R an aliphatic, aromatic or alkylaromatic carbon chain and G + a monoatomic or polyatomic cation and / or a mixture of such cations), preferably chosen from alkylarylsulphonates including sulphonates of dodecylbenzene and tetrapropylbenzene sulphonates, sulphonated olefins, sulphonated fatty acid and fatty acid esters, sodium sulphosuccinate and sulphosuccinamate, sulphosuccinic acid mono and di-esters, sulphosuccinic acid monoamides, N acylamino acids and N-acylproteins, N-acylaminoalkylsulfonates and taurinates, and mixtures thereof; o phosphates (of formula R '- (RO) nPO4_n (3-n) - (3-n) G- with R and R' of the aliphatic, aromatic and / or alkylaromatic carbon chains, G- a monoatomic or polyatomic cation and / or a mixture of such cations, preferably chosen from H-, Na- and K +, and n an integer less than or equal to 3), preferably chosen from mono- and di-esters of phosphoric acid, and their mixtures; amphoteric surfactants and mixtures thereof, in particular betaines of the formula RR'NH-CH3COO- with R and R 'of the aliphatic, aromatic and / or alkylaromatic carbon chains; o sulfobetaines; imidazolium salts; cationic surfactants and mixtures thereof, in particular: non-quaternary ammonium compounds (of formula R'-RfNH (4_n) -X-30 with R and R 'of aliphatic, aromatic and / or alkylaromatic carbon chains X- a monoatomic or polyatomic anion and / or a mixture of such anions and n an integer less than or equal to 4); quaternary ammonium salts (of formula R'-R4N + -X- with R and R 'of the aliphatic, aromatic and / or alkylaromatic carbon chains and X- a monoatomic or polyatomic anion and / or a mixture of such anions), preferably alkyltrimethylammonium, alkylbenzyldimethylammonium, and mixtures thereof; o amine salts; ammonium salts of ethoxylated fatty amines; dialkyldimethylammonium; imidazolinium salts; carboxylic acids, their salts, and their mixtures, in particular the mono- or dicarboxylic aliphatic acids, in particular the saturated acids; fatty acids, and especially saturated fatty acids; formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, 1 stearic acid, hydroxystearic acid, 2-ethylhexanoic acid, behenic acid, nonyl acid, linolenic acid, abietic acid, oleic acid, recinoleic acid, naphthenic acid, phenylacetic acid; dicarboxylic acids including oxalic, maleic, succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acids. The salts of these acids can be used. By carboxylic acid salts is meant the compounds of formula (R-COO-, GT), G- being a cationic group, preferably Na- or NH4-. nonionic surfactants chosen from the group of compounds of formula RCO 2 R 'and R-CONHR' and mixtures thereof, R and R 'being aliphatic, aromatic and / or alkylaromatic carbon chains, and in particular: and di-ethanolamides of polyethoxylated and polypropoxylated fatty acids; polyethoxylated and polypropoxylated fatty amines; polyethoxylated and polypropoxylated block copolymers, for example co-polymers of the Pluronice family marketed by BASF; polyethoxylated and polypropoxylated fatty alcohols and alkylphenols chosen from carboxymethylated fatty alcohol ethoxylates, this family including all of the ethoxylated or propoxylated fatty alcohols including at the end of the chain the -CH 2 -COOH group, of general formula: R 1 -O - (CR2R3-CR4R5-O) r, -CH2-COOH, R1, R2, R3, R4 and R5 being aliphatic, aromatic and / or alkylaromatic carbon chains and n an integer; o amine oxides; alkylimidazolines; o and their mixtures; - and their mixtures.

The additive making it possible to modify the morphology is preferably chosen from the group: anionic surfactants and their mixtures, in particular: carboxylates (of formula R-CO 2 -G 'with R an aliphatic carbon chain, aromatic or alkylaromatic and G + a monoatomic or polyatomic cation and / or a mixture of such cations), preferably chosen from ethoxylated carboxylates, ethoxylated or propoxylated fatty acids, sarcosinates of formula RC (O) N (CH 3) CH 2 COO- and mixtures thereof ; sulphates (of formula R-SO3 "-G" with R an aliphatic, aromatic or alkylaromatic carbon chain and G- a monoatomic or polyatomic cation and / or a mixture of such cations), preferably chosen from alkyl sulphates, alkyl ether sulphates or sulphates of ethoxylated fatty alcohols, nonylphenyl ether sulphates, and mixtures thereof; o sulphonates (of formula R-OSO 3 -G 'with R an aliphatic, aromatic or alkylaromatic carbon chain and G- a monoatomic or polyatomic cation and / or a mixture of such cations), preferably selected from alkylarylsulfonates including dodecylbenzene sulfonates and tetrapropylbenzene sulfonates, sulfonated olefins, sulfonated fatty acid and fatty acid esters, sodium sulfosuccinate and sulfosuccinamate, mono and di esters of sulfosuccinic acid, monoamides of sulfosuccinic acid, N-acylamino acids and N-acylproteins, N-acylaminoalkylsulfonates and taurinates, mixtures thereof; phosphates (of the formula R '- (RO) äPO 4 -n (3-) - (3-n) G "with R and R' of the aliphatic, aromatic and / or alkylaromatic carbon chains, G monoatomic or polyatomic cation and / or a mixture of such cations, preferably chosen from W, Na 'and K +, and n an integer less than or equal to 3), preferably chosen from mono- and diesters of the acid phosphoric acid, and mixtures thereof; cationic surfactants and their mixtures, in particular: non-quaternary ammonium compounds (of formula R'-R'NH (4-n) -X-with R and R 'aliphatic, aromatic and / or alkylaromatic carbon chains, X- a monoatomic or polyatomic anion and / or a mixture of such anions and n an integer less than or equal to 4); quaternary ammonium salts (of formula R'-R4N'-X- with R and R 'of the aliphatic, aromatic and / or alkylaromatic carbon chains and X- a monoatomic or polyatomic anion and / or a mixture of such anions) preferably alkyltrimethylammonium, alkylbenzyldimethylammonium, and mixtures thereof; o amine salts; ammonium salts of ethoxylated fatty amines; dialkyldimethylammonium; imidazolinium salts. Preferably, the additive making it possible to modify the morphology is chosen from the group: anionic surfactants and their mixtures, in particular: sulphates (of formula R-SO3-G + with R an aliphatic, aromatic carbon chain or alkylaromatic and GT a monoatomic or polyatomic cation and / or a mixture of such cations), preferably selected from alkylsulfates, alkylethersulfates or sulfates of ethoxylated fatty alcohols, nonylphenyl ether sulfates, and mixtures thereof; o phosphates (of formula R '- (RO) nPO4- (3- - (3-n) G + with R and R' of the aliphatic, aromatic and / or alkylaromatic carbon chains, and G a monatomic or polyatomic cation and / or a mixture of such cations, preferably chosen from H-, Na- and K-, and n an ent: less than or equal to 3), preferably chosen from mono- and diesters of phosphoric acid, and their mixtures of cationic surfactants and mixtures thereof, in particular: non-quaternary ammonium compounds (of formula R'-RnNH (4_n) -X-with R and R 'aliphatic, aromatic and / or carbonaceous carbon chains; alkylaromatic compounds, X- a monoatomic or polyatomic anion and / or a mixture of such anions and n an integer less than or equal to 4); quaternary ammonium salts (of formula R'-R4N + -X- with R and R ' aliphatic, aromatic and / or alkylaromatic carbon chains and K a monoatomic or polyatomic anion and / or a mixture of such anions), preferably alkyltrimethines ylammonium, alkylbenzyldimethylammonium, and mixtures thereof; More preferably, the additive making it possible to modify the morphology is chosen from the group: alkyl sulphates, such as sodium dodecyl sulphate or SDS; non-quaternary ammonium compounds (of formula R'-RnNH, 4_n) -X- with R and R 'of the aliphatic, aromatic and / or alkylaromatic carbon chains, X- a monoatomic or polyatomic anion and / or a mixture of such anions and n an integer less than or equal to 4), such as methyltrimethylammonium bromide or CTAB. In addition to the additive which makes it possible to modify the morphology, a nonionic surfactant [5], different from those mentioned as being able to serve as an additive, may be added. This surfactant is distinguished from the additive [4] in that it does not allow, without additive, to modify the morphology of the particles obtained. Associated with an additive, it can however modify the impact of said additive. Simple tests make it possible to check whether a nonionic surfactant modifies the morphology of the particles manufactured or not. The optional surfactant may in particular be chosen from all of the compounds of formula R-OR ', R-OH, R- (CH 2 -CH 2 -O), R', the family of polyols R and R 'being aliphatic, aromatic and / or alkylaromatic carbon chains and n is an integer. The optional nonionic surfactant is preferably chosen from polyethoxylated and polypropoxylated nonylphenols (for example the Triton family marketed by Dow Chemicals); polyethoxylated and polypropoxylated fatty alcohols; polyethoxylated and polypropoxylated octylphenols; polyethoxylated and polypropoxylated fatty acid esters; polyethoxylated and polypropoxylated fatty alcohols and alkylphenols, especially ethylene glycol, propylene glycol, glycerol, polyglyceryl esters and their polyethoxylated and polypropoxylated derivatives and polyethylene glycols; anhydrosorbitol esters including polyethoxylated and polypropoxylated sorbitan esters and sorbitan or sorbate esters; alkylpolyglucosides; ethoxylated and propoxylated oils; - and their mixtures.

The optional nonionic surfactant may for example be an anti-foaming agent or a surface tensioning agent, for example the CONTRASPUM K1012 sold by the company Zschimmer and Schwartz. An anti-foaming agent advantageously facilitates the implementation of the process and / or increases its yield. For example, a surface tension agent may increase the effect of the additive.

The definitions of the various surfactants as well as examples can be consulted in the techniques of the engineer, volume K2 after the update n ° 52 (May 2007), Surfactants K342.

The blowing agent [6] may especially be chosen from: the latex family, in particular from styrene acrylates and / or polymethyl acrylates, and from polyvinyl propionates and / or acetates; oxides and salts of polyethylene and / or polypropylene; - and their mixtures. The addition of a porogenic agent advantageously leads to creating porosity in the particles obtained at the end of steps b), c), d) or e). For this purpose, a step of heating these particles may be necessary in order to eliminate the pore-forming agent so that it leaves room for pores. Preferably, the amount of pore-forming agent is greater than 0.5%, preferably greater than 2% and / or less than 25%, preferably less than 10%, the percentages being percentages by weight relative to the first reagent. mother liquor.

To obtain anisotropic particles, the additive is preferably introduced into the mother liquor before the second reagent supplying the anionic groups, and immediately before or after the first reagent supplying Zr4 + and / or Hel- ions. When the mother liquor contains another nonionic surfactant (ie a constituent [5]), and / or a pore-forming agent, these are preferably introduced into the mother liquor immediately before the introduction of the second reagent, and therefore, preferably, after the introduction of the first reagent and the additive. Failure to comply with this order may result in some additives that do not precipitate anisotropic particles. For example, with the sodium dodecyl sulfate (SDS) used as additive, particles of primary derivative of zirconium and / or hafnium anisotropic will be obtained if this additive is introduced immediately before or after the first reagent and before the introduction of the second reagent in the mother liquor. The order of introduction of the various constituents of the mother liquor may for example be: introduction of the polar solvent, introduction of the first reagent, introduction of the SDS additive, introduction of the other optional nonionic surfactant (component ]), introduction of the blowing agent, then introduction of the second reagent On the contrary, particles of primary derivative of zirconium and / or isotropic hafnium will be obtained if this additive is introduced after the second reagent and before the introduction of the first reagent in the mother liquor. With certain additives, however, the order described above is not imperative. Routine tests make it possible to evaluate the impact of the order of introduction of the constituents. The temperature at which the mother liquor is prepared is preferably between the solidification temperature of the solvent of the mother liquor at atmospheric pressure and 50 ° C., preferably between room temperature, typically 20 ° C., and 50 ° C., preferably between 40 ° C and 50 ° C, in order to promote the dissolution of the various components introduced into the solvent of the mother liquor, without starting precipitation reactions of particles. After introducing all the reagents into the mother liquor, it is kept between the solidification temperature of the solvent of the mother liquor at atmospheric pressure and 50 ° C., preferably between room temperature and 50 ° C., preferably between between 40 ° C and 50 ° C, preferably for at least 15 minutes, which advantageously allows better dissolution of the reagents, as well as the achievement of good thermal and chemical homogeneity.

Step b) In step b), the heating temperature is preferably greater than 50 ° C and / or lower than the boiling temperature, preferably less than 100 ° C, preferably less than 90 ° C. The temperature keeping time Ot may be greater than 30 minutes, or even greater than 1 hour and / or less than 10 hours, or even less than 5 hours. The heating is preferably carried out at atmospheric pressure. The rate of rise in temperature v should not be too fast to promote anisotropic growth. It is preferably less than 50 ° C / min, preferably less than 10 ° C / min. The beginning of the heating phase is defined as the moment when the mother liquor is heated, once all the constituents have been introduced. At the end of step b), a final operation chosen from filtration, washing, acid-base neutralization, drying and combinations of these techniques may optionally be applied. All techniques known to those skilled in the art can be used. If drying is performed, an optional disagglomeration step may be performed by any technique known to those skilled in the art. At the end of step b), a suspension of particles or a powder of particles is obtained which, after drying, are insoluble in the polar solvent [1] and hydrolyzable. These particles are amorphous except possibly in case of addition of a dopant, as described below.

Anisotropic particles can also be obtained. If necessary, as explained above, routine tests make it possible to search for such particles.

Step c) Step c) is optional or necessary depending on whether it is desired to manufacture a poorly soluble or acid-soluble secondary derivative in the polar solvent [1], respectively. A derivative is considered poorly soluble if its solubility in water at pH 2 is less than 10-3 mol / l. Otherwise, the derivative is considered soluble. In step c), the primary derivative obtained at the end of step b) may be subjected to a treatment that makes it possible to substitute partially or totally, preferably completely, the anionic groups brought by the second reagent by other anionic groups, called anionic substitution groups, having a high complexing power with zirconium and / or hafnium and preferably selected from oxoanions, anions of column 17 (halides), organic molecules comprising a carboxylate group (R-COO-) , and their mixtures. More preferably, the oxoanions are selected from phosphates, sulphates and carbonates; the halides are selected from chlorides and fluorides; the organic molecules comprising a carboxylate group are selected from formates, acetates, oxalates and tartrates. To effect said substitution, the primary derivative particles are brought into contact with a compound capable of providing the substitution anionic groups.

In step c), the treatment of the primary derivative may, for example, be a carbonation, phosphatation, fluoridation or choridation treatment in order to associate with the zirconium and / or with the hafnium an anionic group carbonate, phosphate, fluoride. or chloride, respectively. For example, after obtaining an anisotropic ZBS at the end of step b), it can optionally be converted into anisotropic basic zirconium carbonate (ZBC) by a carbonation treatment, or converted into anisotropic basic zirconium phosphate by a treatment of phosphating. It is possible to hold the same reasoning with a basic zirconium phosphate initially. A step c) thus makes it possible to obtain compounds that are impossible to obtain in step b), for example because they are soluble in the polar solvent [1] in an acidic medium. In step c), the treatment does not modify the optionally anisotropic nature of the particles obtained in step b).

At the end of step c), a final operation chosen from filtration, washing, acid-base neutralization, drying and combinations of these techniques may optionally be applied. All techniques known to those skilled in the art can be used. If drying is performed, an optional disagglomeration step may be performed by any technique known to those skilled in the art.

Step d) The basic hydrolysis step d) makes it possible to react the primary derivative obtained at the end of step b) or the secondary derivative obtained at the end of step c) and to transform it into zirconium hydrate and / or hafnium. This reaction makes it possible in particular to create porosity within the particles. All techniques known to those skilled in the art can be used to perform the step d) of basic hydrolysis. The basic hydrolysis is carried out by bringing said primary or secondary derivative into contact with at least one source of hydroxide anions OH-, preferably a strong base, in particular NaOH, KOH, or with at least one amine, for the purpose of substituting the anion of said derivative by 0W. The primary or secondary derivative may in particular be presented in the form of: a powder or a suspension, directly obtained in step b) or c), or obtained after resuspension in a polar solvent, preferably in water, especially after filtration, washing and / or drying performed at the end of step b) or c). Said contacting may for example result from: contacting a solid powder of primary or secondary derivative with a liquid basic solution, contacting a solid base with a liquid suspension of primary or secondary derivative contacting a liquid basic solution with a liquid suspension of primary or secondary derivative, bringing into contact a base in gaseous form, for example ammonia, with a liquid suspension of primary or secondary derivative contacting a base in gaseous form, for example ammonia, with a solid powder of primary or secondary derivative. If the primary or secondary derivative is in suspension in a solution, the following conditions will preferably be used: concentration of Zr4- and / or Hf + in said solution: preferably less than mol / l and greater than 0.01 mol / l ; pH: preferably greater than 11; reaction temperature: above the solidification temperature of the solvent, preferably above room temperature, more preferably above 50 ° C and below the boiling point of the solvent, preferably below 90 ° C. In the case where the suspension of primary or secondary derivative used is the mother liquor, the introduction of the source or sources of 0W hydroxide anions is preferably carried out at a temperature below 90 ° C.

At the end of step d), a final operation chosen from filtration, washing, acid-base neutralization, drying and combinations of these techniques may optionally be applied. All techniques known to those skilled in the art can be used. If drying is performed, an optional deagglomeration step may be performed by any known technique d. the skilled person.

Step e) In step el), the calcination conditions modify the porosity index Ip and the specific surface area of the powder. The calcination temperature may especially be greater than 400 ° C. and / or less than 1200 ° C., preferably less than 1100 ° C., more preferably less than 1000 ° C. At temperatures above 1200 ° C, the particles obtained have a low porosity index, that is to say they are dense. At temperatures below 1200 ° C., the particles obtained are porous if the holding time is limited. The maintenance time is generally between 1 hour and 5 hours, preferably about 2 hours.

The invention also relates to dense or porous particles obtained at the end of step e1).

In step e21, the hydrothermal treatment modifies the porosity index Ip and the specific surface area of the powder. The hydrothermal treatment temperature is greater than the boiling point of the polar solvent, preferably water, at the pressure in question, preferably greater than 130 ° C., and / or less than 250 ° C., preferably less than 200 ° C. ° C. At temperatures above 250 ° C, the particles obtained have a low porosity index, that is to say they are dense. At temperatures below 250 ° C., the particles obtained are porous. The hydrothermal treatment may be carried out by heating, in the presence of water vapor, a powder of a primary or secondary derivative, a hydrate or an oxide, said derivative, hydrate or oxide being optionally doped. This treatment can in particular be carried out with: the use of an undried powder of primary or secondary derivative, or of hydrate, the use of a liquid suspension of primary or secondary derivative, of hydrate or of oxide. If the primary or secondary derivative powder, hydrate or oxide is in suspension in a solution, the following conditions are preferred: concentration of Zr4- and / or Hf 4- in the suspensior, total: preferably less than 10 mol / 1 and greater than 0.01 mol / l; PH: preferably between 6 and 8; reaction temperature: preferably greater than 30 ° C, and / or less than 250 ° C, preferably less than 200 ° C; holding time temperature: preferably greater than 1 hour and preferably less than 10 hours. For example, a hydrothermal treatment applied to a primary or secondary derivative of the present invention makes it possible to produce an anisotropic, possibly porous, zirconia. If the derivative is doped, the zirconia obtained will also be doped. If a hydrothermal treatment is applied to a primary or secondary derivative, it may lead to another primary or secondary derivative, a hydrate or an oxide. If a hydrothermal treatment is applied to a hydrate or an oxide, it can lead to a hydrate or an oxide.

The invention also relates to dense or porous particles obtained at the end of step e2).

Calcination or hydrothermal treatment makes it possible to obtain novel crystallized anisotropic forms, in particular zirconium oxide and / or hafnium oxide particles doped with an oxide of an element chosen from yttrium Y, lanthanum La, cerium Ce, scandium Sc, calcium Ca, magnesium Mg and mixtures thereof, the doping oxide being in solid solution with zirconium oxide and / or hafnium oxide, or particles of oxides of zirconium and / or hafnium doped with an oxide of an element selected from Si, Al. S and mixtures thereof, the doping oxide being dispersed in the particle of zirconium oxide and / or hafnium. These particles are optionally porous if the starting particles are porous. Step e) makes it possible, for example, to manufacture a zirconium oxysulfate (crystallized, anisotropic, porous), for example ZrOSO 4, by calcination or by hydrothermal treatment of a ZBS, or else by an oxide-doped zirconia. of yttrium in solid solution, by calcination or hydrothermal treatment of a zirconium hydrate doped with yttrium hydrate in an intimate molecular mixture.

The above rules allow the skilled person to find suitable particles for a particular application by simple routine tests, and in particular to find anisotropic particles. If necessary, it is possible to implement the following experimental plan. At the end of step e), the following steps can thus be carried out: f) optionally, carrying out a first conformity test making it possible to check whether the particle powder obtained at the end of the preceding step presents a minimum percentage of particles having a size in a range of acceptable sizes included in the range 50 nm to 200 m; and a minimum percentage of anisotropic particles; and, optionally, a porosity index, in particular greater than 2; G) if the conformity test is negative, that is to say if said powder is not in conformity, rerun of the previous steps by modifying the manufacturing conditions.

The compliance test in step f) can be, for example, considered positive if more than 20 ° A, or even more than 50%, or even more than 80%, or even more than 90%, or even more than 95%. many of the particles have an anisotropic morphology and if more than 50% or even more than 80% or even more than 90% by number of the particles have a size in the acceptable size range.

These criteria may in particular be used when no step c1 has been carried out. To search for porous particles, the conformity test in step f) can be considered as positive if more than 20%, even more than 50%, even more than 80%, or even more than 90%, or even more than 95% in number of the particles have an anisotropic morphology, and if more than 50% or even more than 80% or even more than 90% by number of the particles have a size in the acceptable size range, and - if the porosity index Ip is greater than 2.

These criteria can in particular be used when a basic hydrolysis step (step d)), or even a calcination step (step e1), or even a hydrothermal treatment step (step e2)) has been performed. Modifying the conditions of basic hydrolysis and / or calcination and / or hydrothermal treatment also act on the porosity index. An increase in the pH during the basic hydrolysis leads to an increase in the porosity index Ip. During calcination and / or hydrothermal treatment, the index [p decreases when the heating temperature increases and / or when the dwell time increases. Whatever the conformity test implemented in step f), the lower limit of the range of acceptable sizes may in particular be 100 nm, 150 nm or even 200 nm and / or the upper limit of the size range. acceptable may include 80 m.

In step g), if the particles are not in conformity, it is possible in particular to determine the conditions of a new synthesis by modifying: in step a) o the nature of the additive; and / or o the concentration of the additive of a concentration increment preferably greater than 5% of the initial concentration and / or less than 15% of the initial concentration, for example 10% of the initial concentration; and / or the order of introduction into the solvent of the various constituents of the mother liquor, in particular by introducing the additive before the second reagent and immediately before or after the first reagent and / or the pH, in particular by fixing it at a value less than 2; and / or where the ratio of the amount of anionic groups to the amount of Zr4 and Hf4 ions is of an increment of preferably greater than 0.3 and / or less than 0.6, for example 0.4; and / or - during step b) o the heating temperature preferably of a temperature increment at most 15 ° C and / or greater than 5 ° C, for example 10 ° C; and / or the temperature keeping time At of an increment of duration preferably greater than 20 minutes and / or less than 40 minutes, for example 30 minutes; and / or o the rate of rise to the heating temperature v, preferably setting it to less than 50 ° C / min, then decreasing it by an increment of 5 ° C / min and / or - when step d) o the heating temperature of a temperature increment preferably at most 15 ° C and / or above 5 ° C, for example 10 ° C; and / or the pH by fixing it preferably to a value greater than 11; and / or during step e1): the heating temperature, preferably fixing it at a temperature below 1200 ° C; and / or the temperature keeping time At of an increment of duration preferably greater than 20 minutes and / or less than 40 minutes, for example 30 minutes; and / or - during step e2): the heating temperature by setting it at a temperature preferably below 250 ° C, or below 200 ° C; and / or the temperature keeping time At of an increment of duration preferably greater than 20 minutes and / or less than 40 minutes, for example 30 minutes.

By increment, we mean a positive or negative variation of a parameter.

The inventors have discovered and recommend the following rules: In order to increase the maximum size of the particles, it is preferable, in step a), to increase the acidity of the mother liquor, and / or the ratio between the quantity of groups. anionic and the amount of Zr4 + and Hf '' ions, and / or the additive content and / or, in step b), to increase the heating temperature and / or the temperature keeping time; to reduce the sphericity index, it is preferable, in step a), to increase the acidity of the mother liquor, and / or the ratio between the quantity of anionic groups and the amount of Zr4 + and Hf ions and / or, in step b), decreasing the heating temperature; to promote the aggregation of the base particles, it is preferable, in step a), to reduce the acidity of the mother liquor, and / or to increase the ratio between the amount of anionic groups and the amount of Zr4- and Hf4- ions and / or, in step b), to increase the temperature holding time; to increase the specific surface area of the particles, it is preferable, in step a) to increase the additive content, and / or in step d) to increase the basic hydrolysis temperature, and / or to step el) lowering the calcination temperature, and / or in step e2) decreasing the temperature of the hydrothermal treatment. It is the same to increase the mesoporous and / or microporous volume; to increase the yield, that is to say the amount of solid matter precipitated, it is preferable, in step a), to reduce the acidity and / or choose a ratio between the amount of anionic groups and the amount of Zr4- and Hf ions between 0.5 and 1.2 and / or increasing the additive content and / or, in step b), increasing the heating temperature and / or to increase the duration of temperature maintenance. The morphology and the sphericity index of the particles are modified by the values of the various parameters defined above. The inventors have discovered and recommend the following rules: by modifying the parameters of a synthesis that has generated needles so as to increase the ratio between the quantity of anionic groups, for example SO.sub.4-, and the amount of Zr.sub.4- and and / or Hf4 and / or in order to increase the additive content, the quantity of needles is increased relative to the quantity of isotropic particles during a subsequent synthesis; By modifying the parameters of a synthesis which has generated platelets in such a way as to increase the acidity of the mother liquor and / or the level of maintenance time, the quantity of platelets relative to the quantity of isotropic particles is increased when a following synthesis; By modifying the parameters of a synthesis having generated stars so as to increase, in the mother liquor, the ratio between the quantity of anionic groups, for example SO42-, and the quantity of Zr4 and / or Hf ions and / or or the additive content, the amount of star is increased relative to the amount of isotropic particles in a subsequent synthesis; By modifying the parameters of a synthesis that has generated sea urchins so as to increase the acidity of the mother liquor and / or with the additive content, the quantity of sea urchins is increased relative to the quantity of isotropic particles during a following synthesis; By modifying the parameters of a synthesis having generated hollow spheres so as to increase, in the mother liquor, the ratio between the quantity of anionic groups, for example SO42-, and the quantity of Zr4 and / or Hf4-ions and or the acidity of the mother liquor, the quantity of hollow spheres is increased relative to the quantity of isotropic particles during a subsequent synthesis; By modifying the parameters of a synthesis having generated lamellae so as to increase, in the mother liquor, the ratio between the quantity of anionic groups, for example 5042-, and the quantity of Zr4 and / or Hf ions and / or the additive content, the amount of lamellae is increased relative to the quantity of isotropic particles during a subsequent synthesis; By modifying the parameters of a synthesis having generated needles so as to reduce the additive content in the mother liquor, the needles are made thinner during a subsequent synthesis; By modifying the parameters of a synthesis having generated needles so as to increase, in the mother liquor, the ratio between the quantity of anionic groups, for example SO42-, and the quantity of Zr4 and Hf ions and / or acidity of the mother liquor, the quantity of stars is increased during a subsequent synthesis, the two forms being able to coexist during the transition; By modifying the parameters of a synthesis having generated needles so as to increase the acidity and / or reduce the additive content of the mother liquor, the quantity of sea urchins is increased during the following synthesis, the two forms being able to coexist during transition; By modifying the parameters of a synthesis which has generated needles so as to increase the acidity and / or the duration of temperature maintenance of the mother liquor, the quantity of hollow spheres is increased, the two forms being able to coexist during the transition; By modifying the parameters of a synthesis which has generated sea urchins in such a way as to increase the acidity and / or the duration of temperature maintenance of the mother liquor, the quantity of hollow spheres is increased, the two forms being able to coexist during the transition. ; By modifying the parameters of a synthesis which has generated platelets so as to increase the additive content of the mother liquor, the quantity of lamellae is increased, the two forms being able to coexist during the transition.

The following table recapitulates the preferred conditions for steps a) and b) to obtain a majority, in number, of particles having certain particular morphologies. In the first column "*" indicates the most important parameters.

The order of introduction of the components into the mother liquor is the preferred order mentioned above. Needles Stars Sea urchins Spheres Lamella Platelets Acidity ([H -]) * 0.6-2 1.2-3 1.2-3 1.2-3 0.6-3 1.6-3 (mol / 1) Concentration in 0.1-1.2 0.1-1.2 0.1-1.2 0.1-1.2 0.1-1.2 0.1-1.2 Zr4- + HÉ- ( mol / l) molar ratio 0.3-1 0.8-2 0.3-1 0.3-1 0.5-2 0.5-1 group. Anion / I (Zr4- + Hf T) * Concentration in 10-3-10-1 10.3-10-1 10.5-10.2 10-3-10-1 10 -'-1 Io -'-Io-2 additive ( mol / 1) Ramp of l0 ~ `-1 10-2-1 10 ~ '` -1 10-2-1 l0.2-10 10 2-1 heating (° C / min) Temperature of 55-80 60- 80 55-80 60-80 60-100 60-80 heating * (° C) Time of 15min-30min-30min-2h lh-5h 30min-5h 1h-10h hold at 2h 2h step The previous rules and conditions, according to preferred embodiments of the invention are not limiting. They make it possible, with the examples described below, to manufacture a powder adapted to a particular application.

Furthermore, the known processes applied to the currently available products have allowed the inventors to make the following observations: the precipitation of basic solutions or the hydrolysis of derivatives known from the prior art lead to an isotropic morphology of the hydrates produced, there is or is not presence of surfactants; A hydrothermal treatment carried out at a temperature above 200 ° C., or even higher than 250 ° C., of a suspension of isotropic particles or of a solution leads to powders of crystallized, possibly anisotropic, dense particles. This type of hydrothermal treatment is described, for example, in the article Morphology of zirconium synthesized hydrothermally from zirconium oxychloride, Journal of the American Ceramic Society, 1992, vol. 75, No. 9, pp. 2515-2519. a hydrothermal treatment carried out at a temperature below 200 ° C. leads to powders of isotropic particles. This type of treatment is described, for example, in the article Nucleation and growth for nanoscale zirconia particles by forced hydrolysis, Journal of Colloid and Interface Science, 1998, vol. 198, pp 87-99. the combustion of a metal salt, the oxidation of a metal, or the calcination at high temperature of precursors lead to powders of dense particles, possibly anisotropic.

The steps of the process just described can be modified to dope the particles manufactured. A dopant or several dopants may be introduced in one or more steps, according to techniques known to those skilled in the art: Step a) In step a), a dopant A chosen from the compounds of elements of column 17 ( halides), compounds of column 1 (alkaline), yttrium Y, scandium Sc, lanthanide, alkaline earth (elements of column 2 of the Periodic Table), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, Fe iron, Mn manganese, Nb niobium, Gallium Ga, Sn tin, Pb lead and their mixtures may be added optionally to the mother liquor. Said compounds can be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, the dopant A is chosen from oxides, hydrates and salts, more preferably from salts. If the dopant A is a compound of sulfur S and / or phosphorus P and mixtures thereof, preferably this compound is SO42 and / or PO43-, preferably introduced by the second reagent.

If the dopant A is an Al aluminum compound, it is preferably chosen from aluminum hydrates. If the dopant A is a Si silicon compound, silicon oxide is preferred. More preferably, the dopant A is soluble in an acid medium.

The dopant A is preferably chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, of cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof, preferably selected from compounds of the elements of column 17 (halides), compounds of elements of column 1 (alkaline), yttrium compounds Y, scandium Sc, lanthanum Ce, Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, P phosphorus, Al aluminum and mixtures thereof. More preferably, the dopant A is chosen from compounds of chlorine Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant A is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures. At the end of step b), the primary derivative obtained will then be a primary derivative of zirconium and / or doped hafnium. For example, if in step a) the stock solution contains a zirconium oxychloride, water, an additive to modify the morphology, a second reagent bringing the anionic groups 5042, and a yttrium salt YC13, the primary derivative obtained at the end of step b) will be a basic zirconium sulfate doped with a basic yttrium sulfate.

In a particular preferred embodiment, a dopant A is added during step a).

Step b) In step b), after obtaining a suspension of particles of primary derivative, possibly doped, or of a powder of particles of primary derivative possibly doped, a dopant B selected from the compounds of elements of the column 17 (halides), compounds of column 1 (alkaline), yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (elements of column 2 of the periodic table of elements) Ti titanium, Si silicon, Al aluminum, Tungsten W, Cr chromium, Mo molybdenum, Vanadium V, Sb antimony, Ni nickel, Cu copper, Zn zinc, Fe iron , Mn manganese, Nb niobium, Galium Ga, Sn tin, Pb lead and their mixtures may be added optionally to the mother liquor. Said compounds can be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt.

Preferably, the dopant B is chosen from oxides, hydrates and salts, more preferably from salts. If the dopant B is an Al aluminum compound, it is preferably chosen from aluminum hydrates. If the dopant B is a Si silicon compound, it is preferably silicon oxide.

The dopant B is preferably chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, of cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof , preferably chosen from the compounds of the elements of column 17 (halides), the compounds of the elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, of cerium Ce, of calcium Ca, Mg magnesium, Si silicon, Al aluminum and mixtures thereof. More preferably, the dopant B is chosen from compounds of chlorine Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, Mg magnesium, Si silicon, Al aluminum and mixtures thereof. Also preferably, the dopant B is chosen from yttrium compounds Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, aluminum Al and mixtures thereof. At the end of step b), the primary derivative obtained will then be a primary derivative of zirconium 5 and / or doped hafnium. The dopant B or a successor of the dopant B may be associated with the primary derivative by any method known to those skilled in the art, for example by an impregnation process or by co-precipitation after resuspension. The addition of a dopant A in step a) does not exclude the addition of a dopant B in step b), and vice versa.

Step c) In step c), optional, before subjecting the primary derivative of zirconium and / or hafnium treatment to substitute the anionic groups of said primary derivative provided by the second reagent by other anionic groups having a high complexing power with zirconium and / or hafnium, a Cl dopant selected from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, scandium Sc, lanthanide, alkaline earth (elements of column 2 of the periodic table of elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, Cr chromium, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu. Zn zinc, Fe iron, Mn manganese, Nb niobium, Galium Ga, Sn tin, Pb lead and their mixtures may be used optionally to dope said primary derivative. Said compounds can be, for example, oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, the dopant C1 is chosen from oxides, the. hydrates, salts, more preferably salts. If the dopant Cl is a compound of sulfur S and / or phosphorus P and mixtures thereof, preferably this compound is SO4- and / or PO43-, preferably introduced by the compound capable of ensuring the substitution of the groups anionic provided by the second reagent If the dopant Cl is an aluminum Al compound, it is preferably chosen from hydrates of aluminum. If the dopant Cl is a Si silicon compound, it is preferably silicon oxide.

The dopant C1 is preferably chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkalis, yttrium Y compounds, scandium Sc, lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof, preferably selected from the compounds of the elements of column 17 (halides), the compounds of the elements of column 1 ', alkaline), yttrium compounds Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant C1 is chosen from chlorine compounds C1, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant Cl is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures. At the end of step c), the secondary derivative obtained will then be a secondary derivative of zirconium and / or doped hafnium. The addition of a dopant A in step a) and / or the addition of a dopant B in step b) does not exclude the addition of a dopant C1 in step c) , and reciprocally. At the end of step c), optional, the secondary derivative obtained, possibly doped, can be doped starting from a dopant C2 chosen from the compounds of elements of the column 17 (halides), the compounds of elements of the Column 1 (alkaline), yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (elements of column 2 of the periodic table of elements), Ti titanium, Si silicon, S sulfur , phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn , niobium Nb. of Ga galium, Sn tin, Pb lead, cobalt Co, ruthenium Ru, Rh rhodium, Pd palladium, Ag silver, Os osmium, Ir irium, platinum Pt. Au gold and their mixtures; preferably the C2 dopant is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium barium, strontium Sr, titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al , tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, of Sn tin, Pb lead, cobalt Co, ruthenium Ru, Rh rhodium, Pd palladium, Osmium silver Os, Ir irium, Pt platinum, Au gold and their mixtures. More preferably, the C2 dopant is chosen from the compounds of the elements of column 17 (halides), the compounds of the elements of column 1 (alkaline), the yttrium compounds Y, scandium Sc, lanthanum La, Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, P phosphorus, Al aluminum and mixtures thereof. Preferably, the dopant C2 is chosen from chlorine compounds Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant C2 is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures. The compounds of column 17 (halides), column 1 (alkaline) compounds, yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (column elements 2 of the periodic table of the elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof may be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt.

Preferably, said compounds are chosen from oxides, hydrates and salts, more preferably from salts. The compounds of cobalt Co, ruthenium Ru, Rh rhodium, palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof may be for example oxides, hydrates, salts, metals. A platinum compound may for example be a platinum salt. Preferably, said compounds of cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Os, iride Ir, platinum Pt, Au gold and mixtures thereof are chosen from oxides, hydrates, salts, metals, more preferably from metals. To boost the secondary derivative, any method known to those skilled in the art, for example by an impregnation process, by co-precipitation after resuspension, can be envisaged. The addition of a dopant A in step a) and / or the addition of a dopant B in step b) and / or the use of a dopant C1 in step c) n does not exclude the use of a C2 dopant and vice versa.

Step d) In step d), when the primary derivative or the secondary derivative, doped or not, is suspended, before carrying out the basic hydrolysis, a dopant D1 chosen from yttrium Y compounds, of scandium Sc, lanthanides, alkaline earths (elements of column 2 of the periodic table of the elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, Pb lead and their mixtures, can optionally be added in the suspension. Said compounds can be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, the dopant D1 is chosen from oxides, hydrates and salts. more preferably from the salts.

More preferably, the dopant D1 is soluble in the polar solvent in which the primary derivative or the secondary derivative is in suspension. The dopant D1 is preferably chosen from yttrium compounds Y, scandium Sc, lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr Ti titanium, Si silicon, phosphorus P sulfur, Al aluminum, Tungsten W, Cr chromium, Mo molybdenum, Vanadium V, Sb antimony, Ni nickel, Cu copper , Zn zinc, Fe iron, Mn manganese, Nb niobium, Galium Ga, Sn tin, Pb lead and mixtures thereof, more preferably Dl dopant is selected from yttrium compounds Y, Sc scandium, lanthanum La, Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, Al aluminum and mixtures thereof. The dopant D1 is preferably introduced into the solvent at the same time as the primary derivative or secondary derivative. For example, if before carrying out the basic hydrolysis of a ZBS, an yttrium salt is added to the suspension, the hydrate obtained will be a zirconium hydrate doped with an yttrium hydrate. The addition of a dopant A in step a) and / or the addition of a dopant B in step b) and / or the use of a dopant C1 in step c) and / or a C2 dopant at the end of step c) does not exclude the addition of a dopant D1 in step d), and vice versa. In a particular embodiment, a dopant A is added to step a) and a dopant D1 in step d), dopant A being different from dopant D1. The hydrate obtained at the end of step d) is then co-doped, and for example is a co-doped zirconium hydrate. After basic hydrolysis, the optionally doped, possibly dried, zirconium and / or hafnium hydrate may be doped with a dopant D2 chosen from the compounds of elements of column 17 (halides), the composed of elements of column 1 (alkaline), yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (elements of column 2 of the periodic table of elements), Ti titanium, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, rhodium rh, palladium Pd, silver Ag, osmium bone, d Iridium Ir, Pt platinum, Au gold and mixtures thereof; preferably, the dopant D2 is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, scandium Sc, lanthanum La. cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, sulfur S phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof; more preferably, the dopant D2 is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, scandium Sc, lanthanum La , Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, P phosphorus, Al aluminum and mixtures thereof. More preferably, the dopant D2 is chosen from the compounds of chlorine Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant D2 is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures.

Compounds of column 17 (halides), column 1 (alkaline) compounds, yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (column elements 2 of the periodic table of the elements), Ti titanium. silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, Mn manganese, Nb niobium, Galium Ga, Sn tin, Pb lead and mixtures thereof may be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, said compounds are chosen from oxides, hydrates and salts, and more preferably, from hydrates, where appropriate. The compounds of cobalt Co, ruthenium Ru, Rh rhodium, palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof can be for example oxides , hydrates, salts, metals. A platinum compound may for example be a platinum salt. Preferably, said compounds of cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Os, iridium Ir, platinum Pt, Au gold and mixtures thereof. are selected from oxides, hydrates, salts, metals, more preferably from metals. To dope the hydrate, any method known to those skilled in the art, for example by an impregnation process, by co-precipitation after resuspension, may be used. This doping operation can be performed several times.

The addition of a dopant A in step a) and / or the addition of a dopant B in step b) and / or the use of a dopant C1 in step c) and / or the use of a C2 dopant at the end of step c) and / or the addition of a D1 dopant before basic hydrolysis does not exclude the use of a D2 dopant after basic hydrolysis, and vice versa.

Step e) In step e), before calcining the derivative obtained at the end of step b) or c), or the hydrate obtained at the end of step d), a dopant El chosen from the compounds of column 17 (halides), column 1 (alkaline) compounds, yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (column 2 elements of periodic table of elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd silver Ag, osmium Os, Ir irium, Pt platinum, Au gold; and mixtures thereof can optionally be used to dope the derivative or hydrate. The dopant E1 is preferably chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, of cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, Pb lead, Co cobalt, Ru ruthenium, Rh rhodium, Pd palladium, Ag silver, Os osmium, Ir irium, Pt platinum, Au gold, and mixtures thereof; more preferably, the dopant E1 is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, scandium Sc, lanthanum La , Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, P phosphorus, Al aluminum and mixtures thereof. More preferably, the dopant El is chosen from chlorine compounds Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant E1 is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures.

Compounds of column 17 (halides), column 1 (alkaline) compounds, yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (column elements 2 of the periodic table of the elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof may be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, said compounds are chosen from oxides and hydrates. the salts, more preferably, if appropriate, among the oxides. The compounds of cobalt Co, ruthenium Ru, Rh rhodium, palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof can be for example oxides , hydrates, salts, metals. A platinum compound may for example be a platinum salt.

Preferably, said compounds of cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Os, iride Ir, platinum Pt, Au gold and mixtures thereof are chosen from oxides, hydrates, salts, metals, more preferably from metals. The oxide obtained after calcination will be a doped oxide. Doping can be carried out by any technique known to those skilled in the art, in particular by adding a powder or impregnation by means of a suspension. The addition of a dopant A in step a) and / or the addition of a dopant B in step b) and / or the use of a dopant C1 in step c) and / or the use of a C2 dopant at the end of step c) and / or the addition of a D1 dopant before basic hydrolysis and / or the use of a D2 dopant after basic hydrolysis does not exclude the use of an El dopant before calcination, and vice versa. After the calcination step, the possibly doped, optionally dried, zirconium and / or hafnium oxide may be doped with an E2 dopant chosen from the compounds of elements of column 17 (halides ), compounds of column 1 (alkaline), yttrium Y, scandium Sc, lanthanide, alkaline earth (column 2 of the Periodic Table of Elements), Ti titanium Si, S, P, Al, Tungsten W, Cr, Mo, V, Sb, Ni, Cu, Zn , iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Bone, iridium Ir, Pt platinum, Au gold and mixtures thereof; preferably, the dopant E2 is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, of scandium Sc, of lanthanum La, of cerium Ce, praseodymium Pr, neodymium Nd, calcium Ca, magnesium Mg, barium Ba, strontium Sr, titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, rhodium Rh, palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof; more preferably, the dopant E2 is chosen from the compounds of elements of column 17 (halides), the compounds of elements of column 1 (alkaline), the compounds of yttrium Y, scandium Sc, lanthanum La , Ce cerium, Ca calcium, Mg magnesium, Si silicon, S sulfur, P phosphorus, Al aluminum and mixtures thereof. More preferably, the dopant E 2 is chosen from chlorine compounds Cl, fluorine F, sodium Na, potassium K, yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, phosphorus P, aluminum Al and mixtures thereof. More preferably, the dopant E2 is chosen from compounds of yttrium Y, scandium Sc, lanthanum La, cerium Ce, calcium Ca, magnesium Mg, silicon Si, sulfur S, aluminum Al and their mixtures.

Compounds of column 17 (halides), column 1 (alkaline) compounds, yttrium Y, scandium Sc, lanthanide, alkaline earth compounds (column elements 2 of the periodic table of the elements), titanium Ti, silicon Si, sulfur S, phosphorus P, aluminum Al, tungsten W, chromium Cr, molybdenum Mo, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, galium Ga, tin Sn, lead Pb and mixtures thereof may be for example oxides, hydrates, salts, carbides, nitrides, metals. An yttrium compound may for example be an yttrium salt, for example the YC13 salt. Preferably, said compounds are selected from oxides, hydrates, salts, more preferably from salts. The compounds of cobalt Co, ruthenium Ru, rhodium Rh, (palladium Pd, silver Ag, osmium Os, Ir irium, platinum Pt, Au gold and mixtures thereof may be for example For example, a platinum compound may be a platinum salt, such as cobalt Co, ruthenium Ru, rhodium rhodium, palladium Pd, silver Ag, oxides, hydrates, salts and metals. , osmium Os, Ir irium, Pt platinum, Au gold and mixtures thereof are selected from oxides, hydrates, salts, metals, more preferably from metals, doping said oxide may be carried out by any method known to those skilled in the art, for example by an impregnation process.

The addition of a dopant A in step a) and / or the addition of a dopant B in step b) and / or the use of a dopant C1 in step c) and / or the use of a C2 dopant at the end of step c) and / or the addition of a D1 dopant before basic hydrolysis and / or the use of a D2 dopant after basic hydrolysis and / or the use of an El dopant before calcination does not exclude the use of an E2 dopant after calcination, and vice versa.

In a variant of the invention, a triple doping of the zirconia is carried out by adding a first, a second and a third dopant. For example, a Y-doped ZBS derivative is made by adding an yttrium salt. Then a hydrate co-doped Y / Ce by adding a cerium salt. Finally, before calcination, an aluminum salt is added and a Y / Ce / Al doped zirconia is obtained. In general, the use of a dopant can be carried out independently of the use of one or more other dopants. However, for the dopant to be located inside the particle in the form of a defined compound, a solid solution, or an intimate molecular mixture, it is preferable that the dopants are of type A and / or or C1 and / or D1 and / or E1. In order for the dopant to be located inside the particle in the form of a dispersion or inclusion, or to be located on the surface of the particle, it is preferable that the dopant is of type B and / or C2 and / or D2 and / or E2.

The molar quantity of dopant in the particles may be less than 40%, less than 20%, less than 10%, or even less than 5% or even less than 3%.

EXAMPLES The following examples are provided for illustrative purposes and do not limit the invention.

Comparative Example 1 Powder Excluding the Invention In a Pyrex 1 1 beaker, 110 g of zirconium oxycholide are dissolved in 300 ml of deionized water, followed by the addition of 28 g of sodium sulphate and 500 ml with deionized water. The acidity of the mother liquor is 1.2, the concentration of (Zr4- + Hf 4-) is 0.6 mol / l and the molar ratio between the anionic groups SO42 and (Zr4 + Hf i-) is 0.6. After complete dissolution of the reagents, the solution is carried, still stirring, at 90 ° C with a heating ramp of 1 ° C / min. The solution is kept at 90 ° C for 1 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The powder thus obtained has a specific surface area of 3 m 2 / g and is amorphous by X-ray diffraction. The particles of ZBS are in a characteristic spherical quasi-spherical form. In a 1 1 Teflon PTFE beaker, the cake is then suspended in 250 ml of deionized water. In a second 1 PTFE Teflon beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered. then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO.

The powder thus obtained has a specific surface area of 320 m 2 / g. The sum of the mesoporous and microporous volumes of 0.18 cm3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in a quasi-spherical form similar to that of the starting ZBS derivative. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly velocity VVH) at 500 ° C. The powder thus obtained has a specific surface area of 60 m 2 / g; the sum of the mesoporous and microporous volumes is 0.12 cm3 / g; the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by X-ray diffraction. The zirconia particles are in a quasi-spherical form similar to that of the initial particles of the ZBS derivative (shown in FIG. ) and ZHO. Example 2: Powder in the form of needles In a pyrex 1 1 beaker, 210 g of zirconium oxychloride in 300 ml of deionized water are placed in solution at 50 ° C. with stirring, then 2.5 g of sodium dodecyl sulphate or SDS, then 52 g of sodium sulphate are added and the mixture is made up to 500 ml with deionized water. the temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acidity of the mother liquor is 2, the concentration of (Zr4T + Hf T) is 1 mol / l, the molar ratio between the anionic groups SO42 and (Zr4- + Hf'-) is 0.6, and the concentration of SDS additive is 0.02 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring, to 70 ° C with a heating ramp of 1 ° C / min. The solution is kept at 70 ° C for 15 min and then allowed to cool freely to below 50 ° C.

This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 6 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of needles of length L between 0.5 and 3 m, of width 1 included between 0.3 and 0.8 m, and thickness e between 0.25 and 0.8 m. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. In a 1 1 Teflon PTFE beaker, the cake is then put into suspension in 250 ml of deionized water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO.

The powder thus obtained has a specific surface area of 360 m 2 / g and is amorphous by X-ray diffraction. The sum of the mesoporous and microporous volumes is 0.25 cm 3 / g. The ZHO particles are in the form of needles of length L between 0.5 and 3 m, width 1 between 0.3 and 0.8 m, and thickness e between 0.25 and 0 , 8 m, similar to those of the starting ZBS derivative. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, then shaken with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly velocity VVH) at 500 ° C. The powder thus obtained has a specific surface area of 120 m 2 / g, the sum of the mesoporous and microporous volumes is 0.20 cm 3 / g and the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by diffraction with X-rays. The zirconia particles are in the form of needles of length L between 1 and 2 m, width 1 between 0.3 and 0.8 m, and thickness e between 0.25 and 0.8 m, similar to the initial particles of the derivative ZBS (shown in Figure 3b) and ZHO. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. Example 3: Powder in the form of needles In a beaker of 1 1 in Pyrex, 110 g of zirconium oxycholide are dissolved in 300 ml of deionized water while stirring, and then 20 g of cetyltrimethylammonium bromide or CTAB are added, followed by the addition of 42 g of sodium sulphate and to 500 ml with deionized water. The temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acicity of the mother liquor is 1.2, the concentration of (Zr4- + Hf 4 ') is 0.6 mol, the molar ratio between the anionic groups SO422- and (Zr4- + Hf) is 0.9, and the CTAB additive concentration is 0.1 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring, to 60 ° C with a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 30 min and then allowed to cool freely to below 50 ° C.

This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 2 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of needles of length L ranging between 20 and 40 m, of width 1 inclusive. between 2 and 5 m, and thickness e between 1.5 and 5 m. For each of these needles, L / l is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. In a 1 1 Teflon PTFE beaker, the cake is then put into suspended in 250 ml of deionized water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO. The powder thus obtained has a specific surface area of 350 m 2 / g, the sum of the mesoporous and microporous volumes is 0.20 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in a d-form. needles of length L between 20 and 40 m, width 1 between 2 and 5 m, and thickness e between 1.5 and 5 m. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. The needles are similar to those of the starting ZBS derivative. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hour hourly VVH volume velocity) at 500 ° C.

The powder thus obtained has a specific surface area of 100 m 2 / g, the sum of the mesoporous and microporous volumes is 0.18 cm 3 / g and the powder is crystallized under a mixture of quadratic and monoclinic phases determined by X-ray diffraction. zirconia particles are in the form of needles of length L between 15 and 30 m, width 1 between 1 and 4 m, and thickness e between 0.7 and 4 m. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. The needles are similar to those of the ZBS derivative (shown in FIG. 3c) and ZHO initials. Example 4: Powder in the form of stars In a Pyrex 1 1 beaker, 110 g of zirconium oxycholide are dissolved in 300 ml of deionized water at 50 ° C. and then 5 g of bromide are added. cetyltrimethylammonium or CTAB then 50 ml of 36% hydrochloric acid HCI, then 28 g of sodium sulfate are added and the mixture is made up to 500 ml with deionized water. The temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acidity of the mother liquor is 2.4, the concentration of (Zr4- + Hf -) is 0.6 mol / l, the molar ratio between the anionic groups 5042- and (Zr4 + Hf -) is 0.6, and the CTAB additive concentration is 0.025 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring. at 60 ° C with a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 1 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 3 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of stars of between 5 and 40 m in length. In a 1 1 Teflon PTFE beaker, the cake is then suspended in 250 ml of deionized water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of water. permutated water on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO.

The powder thus obtained has a specific surface area of 340 m 2 / g, the sum of the mesoporous and microporous volumes is 0.20 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in the form of stars of length between 5 and 40 m, similar to those of the ZBS derivative of departure.

The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly velocity VVH) at 500 ° C. The powder thus obtained has a specific surface area of 90 m 2 / g, the sum of the mesoporous and microporous volumes is 0.18 cm 3 / g and the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by diffraction with X-rays. The zirconia particles are in the form of stars of length between 5 and 30 m, similar to that of the initial particles of the derivative ZBS (shown in Figure 3d) and ZHO.

As shown in Figure 3d, the ZBS star forming needles have a tapered and pointed shape. These needles are substantially of revolution about their longitudinal axis. The surface of their cross section, substantially discoidal, decreases gradually as the tip (s). In addition, the lateral outer surface of the needles is particularly smooth. ZHO and zirconia needles have similar shapes. EXAMPLE 5 Powder in the form of sea urchins In a Pyrex 1 1 beaker, 110 g of zirconium oxycholide in 300 ml of deionized water are dissolved at 50 ° C. with stirring, then 0.5 g of cetyltrimethylammonium bromide or CTAB, then 28 g of sodium sulfate are added and made up to 500 ml with deionized water. The temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acic.ity of the mother liquor is 1.2, the concentration of (Zr4- + Hf -) is 0.6 mol / l, the molar ratio between the anionic groups SO4 '- and (Zr4-- + Hf4 +) is 0.6, and the concentration of CTAB additive is 0.0025 mol / l. The presence of foam on the surface of the solution is observed.

The solution is then brought, still stirring, to 60 ° C with: a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 1 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 6 m 2 / g and is amorphous by X-ray diffraction. The particles of ZBS are present under. a form of aggregates of dimension between 10 and 30 m consisting of particles of length L of 2 m in the form of needles and stars. In a 1 1 Teflon PTFE beaker, the cake is then suspended in 250 ml of deionized water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained consists of a zirconium hydrate, or ZI [O. The powder thus obtained has a specific surface area of 360 m 2 / g, the sum of the mesoporous and microporous volumes is 0.25 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in a d-form. aggregates whose largest dimension is between 10 and 30 m, consisting of particles of 2 gm in the form of needles and stars, similar to those of the starting ZBS derivative. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly velocity VVH) at 500 ° C. The powder thus obtained has a specific surface area of 120 m 2 / g, the sum of the mesoporous and microporous volumes is 0.21 cm 3 / g and the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by diffraction with X-rays. The zirconia particles are in the form of aggregates, the largest dimension of which is between 5 and 20 m, consisting of 1 m particles in the form of needles and stars, similar to those initial particles of the ZBS derivative (shown in Fig. 3e) and ZHO. Example 6: Powder in the form of platelets In a Pyrex 1 1 beaker, 110 g of zirconium oxycholide in 300 ml of deionized water are dissolved at 50 ° C. and 5 g of cetyltrimethylammonium bromide are then added. or CTAB then 25 ml of 36% hydrochloric acid HC1, then 28 g of sodium sulphate are added and made up to 500 ml with deionized water. The temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acidity of the mother liquor is 2, the concentration of (Zr4- + Hf'-) is 0.6 mol / l, the molar ratio between the anionic groups SO42- and (Zr4- + Hf1-) is 0.6, and the CTAB additive concentration is 0.025 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring, to 60 ° C with a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 1 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS.

The ZBS powder thus obtained has a specific surface area of 3 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of a mixture of approximately 50% quasi-form particles. spherical called grape bunch and 50% platelets of thickness e between 1 and 3 m, length L between 10 and 20 m, and width 1 between 10 and 15 m. For each of these platelets, L / 1 is less than 1.5. In a 1 1 Teflon PTFE beaker, the cake is then suspended in 250 ml of deionized water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to I 1 by addition of 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of water. swapped on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO. The powder thus obtained has a specific surface area of 340 m 2 / g, the sum of the mesoporous and microporous volumes is 0.22 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in the form of a mixture of about 50% of particles of quasi-spherical shape called grape bunch and 50% of platelets with a thickness e of between 1 and 3 m, of length L between 10 and 20 m, and of width 1 included between 10 and 15 m, similar to those of the starting ZBS derivative. For each of these platelets, L / 1 is less than 1.5.

The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a hourly volume velocity VVH of 300 h -1) at 500 ° C. The powder thus obtained has a specific surface area of 80 m 2 / g, the sum of the mesoporous and microporous volumes is 0.15 cm 3 / g and the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by diffraction with X-rays. The zirconia particles are in the form of a mixture of about 50% of particles of quasi-spherical shape called grape bunch and 50% of platelets with a thickness e of between 1 and 2 m in length. L between 8 and 15 m, and width 1 between 8 and 12 m. This form is similar to that of the initial particles of the ZBS derivative (shown in Figure 3f) and ZHO. For each of these platelets, L / 1 is less than 1.5. EXAMPLE 7 Powder in the form of hollow particles In a Pyrex 1 1 beaker, 55 g of zirconium oxycholide in 300 ml of deionized water are stirred at 50 ° C. and then 2.5 g of cetyltrimethylammonium bromide or CTAB then 25 ml of 36% hydrochloric acid HCl, then 7 g of sodium sulphate are added and the mixture is made up to 500 ml with deionized water, the temperature is adjusted to 50.degree. 15 minutes after complete dissolution of the reagents. The acidity of the mother liquor is 1.2, the concentration of (Zr4- + Hf'-) is 0.3 mol / l, the molar ratio between the anionic groups SO42- and (Zr4 '+ Hf -) is 0.4, and the concentration of CTAB additive is 0.015 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring, to 60 ° C with a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 1 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 2 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of a mixture of approximately 50% of quasi-spherical particles known as bunch of grapes and 50% 0 of hollow particles, with a spherical index between 0.85 and 0.9, with a larger outside diameter D of between 50 and 300 m, and with a larger inside diameter D 'of between 35 and and 280 m. The thickness of the wall of these spheres is between 5 and 20 m, and the D / I ratio is less than 2. In a 1 1 PTFE Teflon beaker, the cake is then suspended in 250 ml. of permutated water. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered. then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water. on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO.

The powder thus obtained has a specific surface area of 280 m 2 / g, the sum of the mesoporous and microporous volumes is 0.15 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in the form of a mixture of 50% particles of quasi-spherical shape called grape bunch and 50% of hollow particles, sphericity index between 0.85 and 0.9, larger outside diameter D between 50 and 300 m, and larger inside diameter D between 35 and 280 m. The thickness of the wall of these spheres is between 5 and 20 m, and the ratio D / D 'is between 1.1 and 1.5. These forms are similar to those of the starting ZBS derivative. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C., then spun with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly velocity VVH) at 500 ° C. The powder thus obtained has a specific surface area of 60 m 2 / g, the sum of the mesoporous and microporous volumes is 0.10 cm 3 / g and the powder is crystallized in the form of a mixture of quadratic and monoclinic phases determined by diffraction with X-rays. The zirconia particles are in the form of a mixture of about 50% of particles of quasi-spherical shape called grape bunches and 50% of hollow particles, with a sphericity index between 0.85 and 0.9, larger outer diameter D between 50 and 300 4m, and larger internal diameter D between 35 and 280 m. The thickness of the wall of these spheres is between 5 and 20 m, and the ratio D / D 'is between 1.1 and 1.5. This form is similar to that of the initial particles of the ZBS derivative (shown in Figure 3g) and ZHO. Example 8: Powder in lamellar form In a Pyrex 1-liter beaker, 110 g of zirconium oxycholide are dissolved in 300 ml of deionized water at a temperature of 50 ° C., and then 100 g of bromide are added. cetyltrimethylammonium or CTAB, then 28 g of sodium sulfate are added and made up to 500 ml with deionized water. The temperature is adjusted to 50 ° C and maintained for 15 minutes after complete dissolution of the reagents. The acidity of the mother liquor is 1.2, the concentration of (Zr4` + Hf -) is 0.6 moUl, the molar ratio between the anionic groups SO42- and (Zr4- + Hf4) is 0, 6, and the CTAB additive concentration is 1 mol / l. The presence of foam on the surface of the solution is observed. The solution is then brought, still stirring, to 60 ° C with a heating ramp of 1 ° C / min. The solution is kept at 60 ° C for 1 h and then allowed to cool freely to below 50 ° C.

This procedure generates a suspension consisting of a solid phase and a liquid supernatant as well as foam. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a basic zirconium sulfate, ZBS. The ZBS powder thus obtained has a specific surface area of 4 m 2 / g and is amorphous by X-ray diffraction. The ZBS particles are in the form of a mixture of about 50% quasi-spherical shaped particles. said bunch of grapes and 50% of slats composed of 10 to 15 platelets of thickness e of 1 to 2 m length L between 10 and 20 m, and width 1 between 10 and 15 m. For each of these platelets, L / 1 is less than 1.5. In a 1 1 Teflon PTFE beaker, the cake is then suspended in 250 ml of deionized water. In a second 1-liter beaker made of Teflon PTFE, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The suspension is then filtered and then washed with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid. The suspension is then filtered and then washed with 1 l of deionized water. on a Buchner type filter. The cake obtained is resuspended in 1 l of deionized water and the pH is adjusted to 1 liter by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 liter of water. swapped on a Buchner type filter. The cake obtained is constituted by a zirconium hydrate, or ZHO. The powder thus obtained has a specific surface area of 340 m 2 / g, the sum of the mesoporous and microporous volumes is 0.25 cm 3 / g and the powder is amorphous by X-ray diffraction. The ZHO particles are in the form of a mixture of about 50% of particles of quasi-spherical shape called grape bunch and 50 ° / o of platelets composed of 10 to 15 platelets of thickness e of 1 to 2 m, length L between 10 and 20 m, and width 1 between 10 and 15 m, similar to those of the particles of the starting ZBS derivative. For each of these placettes, L / 1 is less than 1.5. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C. and then stirred with agate mortar. The powder obtained is calcined in air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a hourly volume velocity VVH of 300 hours) at 500 ° C. The powder thus obtained has a specific surface area of 100 m 2 / g, the sum of the mesoporous and microporous volumes is 0.20 cm 3 / g and is crystallized in the form of a mixture of quadratic and monoclinic phases determined by X-ray diffraction. The zirconia particles are in the form of a mixture of about 50% of particles of quasi-spherical shape called grape bunch and 50% of platelets composed of 10 to 15 platelets of thickness e of 0.5 to 1 m, length L between 8 and 15 m, and width 1 between 8 and 12 m. This form is similar to that of the initial particles of the ZBS derivative and ZHO. For each of these platelets, L / 1 is less than 1.5. Example 9: Powder in the form of needles, with a dopant introduced in the form of yttrium chloride YC13 In a 1 1 PTFE Teflon beaker, 100 g of the ZBS of Example 3 is suspended in 250 ml of permuted water, then 80 g of yttrium chloride solution YC13 at 1 mol / l (D1 dopant) are added. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid, and then adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a zirconium hydrate doped with an yttrium hydrate, or ZHY. The main physicochemical properties of the powder thus obtained are given in Table 1b. This powder has a specific surface area of 300 m 2 / g, the sum of mesoporous and microporous volumes of 0.18 cm 3 / g and is amorphous by X-ray diffraction. The particles of ZHY are in the form of needles of length L between 20 and 40 m, width 1 between 2 and 5 m, and thickness e between 1.5 and 5 m, similar to that of the starting ZBS derivative. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, then shaken with agate mortar. The powder obtained is calcined under air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 ml / min, ie a 300 hr hourly volume velocity VVH) at 800 ° C.

The powder thus obtained has a specific surface area of 50 m 2 / g, the sum of the mesoporous and microporous volumes is 0.15 cm 3 / g and the powder is crystallized in quadratic form determined by X-ray diffraction. The particles of zirconia doped with 3 mol% of Y 2 O 3 are in the form of needles of length L between 15 and 30 m, width 1 between 1 and 4 m, and thickness e between 0.7 and 4 m, similar to initial particles of ZBS derivative and initial ZHY. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. Example 10: Powder in the form of needles, with a dopant introduced under the YC11 Yttrium Chloride Form In a Teflon PTFE 1 1 beaker, 100 g of the ZBS of Example 3 is suspended in 250 ml of deionized water, 220 g of yttrium chloride YC13 solution are added. at 1 mol / l. In a second 1 1 Teflon PTFE beaker, 25 g of NaOH sodium hydroxide are dissolved in 250 ml of deionized water. The basic solution of sodium hydroxide is then gradually added to the suspension of ZBS; the pH of the final suspension is between 12 and 13. The suspension is then heated to 90 ° C. with a heating ramp of 1 ° C./min. The suspension is maintained at 90 ° C for 2 h and then allowed to cool freely to below 50 ° C. This procedure generates a suspension consisting of a solid phase and a liquid supernatant. The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The cake thus obtained is then resuspended in 1 l of deionized water and the pH is adjusted to 5 by addition of 0.1 N hydrochloric acid, and then adjusted to 11 by adding 1 N ammonia (NH 4 OH). The suspension is then filtered and then washed twice with 1 l of deionized water on a Buchner type filter. The cake obtained consists of a zirconium hydrate doped with an yttrium hydrate, or ZHY. The powder thus obtained has a specific surface area of 300 m 2 / g, the sum of the mesoporous and microporous volumes is 0.15 cm 3 / g, and the powder is amorphous by X-ray diffraction. The particles of ZHY are in a form needles of length L between 20 and 40 m, width 1 between 2 and 5 m, and thickness e between 1.5 and 5 m, similar to those of the starting ZBS derivative. For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1.

The cake obtained is then dried in an oven for at least 12 hours at 110 ° C, and then stirred with agate mortar. The powder obtained is calcined in air for 2 hours (temperature ramp of 2 ° C./min, air flow rate of 100 m.sup.-1, a hourly volume velocity VVH of 300 h -1) at 800 ° C. The powder thus obtained has a specific surface area of 45 m 2 / g, the sum of the mesoporous and microporous volumes is 0.13 cm 3 / g and the powder is crystallized in a cubic form determined by X-ray diffraction. 8% molar doped zirconia particles of Y2O3 are in the form of needles of length L between 15 and 30 m, width 1 between 1 and 4 m, and thickness e between 0.7 and 4 m, similar to the initial particles of the For each of these needles, L / 1 is between 1.67 and 50, and the thickness e is greater than 0.5 times the width 1. The following tables specify the compositions of the manufactured examples. , as well as their loss on fire.

Example Na2O SiO2 Fe2O3 CaO Al2O3 Cl SO4` Loss at (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (/ o) fire at 1000 C (%) 1 ZBS <100 <100 <50 <50 <50 <100 15 65 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1.5 2 ZBS <100 <100 <50 <50 <50 <100 12 68 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1.2 3 ZBS <100 <100 <50 <50 <50 <100 16 64 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1 , 2 4 ZBS <100 <100 <50 <50 <50 <100 19 68 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 < 0.01 1.1 ZBS <100 <100 <50 <50 <50 <100 18 70 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 < 50 <100 <0.01 1.5 6 ZBS 1 <100 <100 <50 <50 <50 <100 12 65 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1.5 7 ZBS <100 <100 r <50 <50 <50 <100 8 60 ZHO <100 <100! <50 <50 <50 <100 <0.01 45 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1.2 8 ZBS <100 <100 <50 <50 <50 <100 15 65 ZHO <100 <100 <50 <50 <50 <100 <0.01 50 Zirconia <100 <100 <50 <50 <50 <100 <0.01 1.5 9 ZBS <100 <100 <50 <50 <50 - 16 64 ZHY 150 <100 <50 <50 <50 5.2 <0.01 55 Zirconia 150 <100 <50 <50 <50 5.2 <0.01 0.7 ZBS <100 <100 <50 <50 < 50 - 16 64 ZHY 300 <100 <50 <50 <50 13.5 <0.01 56 Zirconia 300 <100 <50 <50 <50 13.5 <0.01 0.8 The following tables provide measurement results performed on the particles of the examples.

 P is the sum of the mesoporous volume and the microporous volume.

Dpores refers to the average equivalent diameter of pores less than 50 nm in size.

 Mono refers to the monoclinic phase.

 Quadra refers to the quadratic phase.

 Cub refers to the cubic phase. Phase Ex. Specific Dimensions (m) P (cm3 / g) DPOieS crystalline sphericity (mz / g) (nm) DRX 1 ZBS 0.83 Max Dim = 20 3 - - Amorphous ZHO 0.83 Max Dim = 20 320 0.18 3 Amorphous Zirconia 0.83 Max Dim = 12 60 0.12 3 55% Mono L = 0.5 to 3 2 ZBS 0.2 1 = 0.3 to 0.8 6 - - Amorphous e = 0.25 to 0.8 L = 0.5 to 3 ZHO 0.2 I = 0.3 to 0.8 360 0.25 3 Amorphous e = 0.25 to 0.8 L = 1 to 2 Zirconia 0.2 1 = 0.3 to 0.8 120 0.20 3.5 45% Mono e = 0.25 to 0.8 L = 20 to 40 3 ZBS 0.14 1 = 2 to 5 3 - - Amorphous e = 1.5 to 5 L = 20 to 40 ZHO 0.14 1 = 2 to 5 350 0.20 3 Amorphous e = 1.5 to 5 L = 15 to 30 Zirconia 0.14 1 = 1 to 4 100 0.18 3 55 % Mono e = 0.7 to 4 4 ZBS 0.14 to 40 3 - - Amorphous ZHO 0.14 5 to 40 340 0.20 3 Amorphous Zirconia 0.14 5 to 30 90 0.18 3 55% Mono ZBS 0, 2 10 to 30 6 - - Amorphous ZHO 0.2 10 to 360 360 0.25 3 Amorphous Zirconia 0.2 5 to 120 120 0.21 3 45% Mono L = 10 to 20 6 ZBS 0.33 1 = 10 to 15 3 - - Amorphous e = 1 to 3 L = 10 to 20 ZHO 0.33 1 = 10 to 15 340 0.22 3 Amorphous e = 1 to 3 L = 8 to 15 Zirconia 0.33 1 = 8 to 12 80 0.15 3 50% Mono e = 1 to 2 7 ZBS 0.85 to 0.9 D = 50 to 300 2 Amorphous D = 35 to 280 ZHO 0.85 at 0.9 D = 50 to 300 280 0.15 3 Amorphous D = 35 to 280 D = 50 to 300 Zirconia 0.85 to 0.9 D '= 35 to 280 60 0.10 3 60% Mono to 15 platelets 8 ZBS 0.33 L = 10 to 20 4 Amorphous = 10 to 15 e = 1 to 2 10 to 15 platelets ZHO 0.33 L = 10 to 20 340 0.25 3 Amorphous 1 = 10 to 15 e = 1 to 2 10 to 15 platelets Zirconia 0.33 L = 8 to 15 100 0.20 3 50 ° / Mono 1 = 8 to 12 e = 0.5 to 1 Index of Area DPores Phase Ex. Dimension (am) specific P (cm3 / g) crystalline sphericity (m3 / g) (nm) DRX L = 20 to 40 9 ZHY 0.2 1 = 2 to 5 300 0.18 3 Amorphous e = 1.5 to 5 L = 15 to 30 1 100% 00% Zirconia 0.2 1 = 1 to 4 50 0.15 3 e = 0.7 to 4 Quadra L = 20 to 40 10 ZHY 0.2 1 = 2 to 5 300 0.15 3 Amorphous e = 1.5 to 5 L = 15 to 30 Zirconia 0.2 1 = 1 to 4 45 0.13 3 100% Cub e = 0.7 to 4 As it is now clear, the invention makes it possible to manufacture new anisotropic particles or particles consisting of basic anisotropic rticules which advantageously make it possible to create a body or a powder having a high porosity. Such bodies and powders are particularly useful in applications to catalysis or filtration. In addition, these anisotropic particles or particles consisting of anisotropic base particles may themselves be of a porous material, and in particular may have microporosity and / or mesoporosity. These microporosity and / or mesoporosity are particularly useful for the catalysis of certain chemical reactions.

Claims (20)

REVENDICATIONS1. Process for manufacturing a powder of zirconium and / or hafnium hyc: spleen particles, doped or not, and mixtures thereof, said process comprising a basic hydrolysis step of a starting particle powder and a zirconium and / or hafnium derivative of formula M (OH) n (N ') y (OH 2) z M being Zr 4 -, H 14 -, or a mixture of Zr 4 and Hf, N' being an anion or a mixture of anions, the indices x and y being strictly positive numbers, z being a positive or zero number, said material having a solubility in water at a temperature below 20 ° C of less than 10-3 mol / l, said dopable or non-dopable derivative, and said starting particles being constituted of aggregated or unaggregated base particles having a sphericity index of less than 0.6. 2. Method according to the preceding claim, wherein said derivative is selected from basic zirconium sulphate and / or hafnium, doped or not, the basic phosphate of zirconium and / or hafnium, doped or not, the basic carbonate zirconium and / or hafnium doped or not, and mixtures thereof. 3. Powder having a maximum particle size D99.5 of less than 200 m and having a porosity index Ip greater than 2, the porosity index being equal to the ratio Asr / Asg where Asg is the theoretical geometric specific surface area of the particles powder; - Asr is the measurement of the actual specific area by BET; said powder comprising more than 20% by number of basic particles, aggregated or not, having a sphericity index of less than 0.6, and consisting of a zirconium and / or hafnium hydrate of formula MOX (OH) y ( OH2) z, M being Zr4-, Hf-, or a mixture of Zr4_ and Hf4 *, the indices x and z being positive or zero numbers, the index y being a positive number, and 2x + y being equal to 4; , doped or not, or a mixture of such hydrates. 4. Powder according to the preceding claim, comprising more than 90% by number of said base particles. The powder of any of claims 3 and 4, wherein said base particles have a sphericity index greater than 0.02. 6. Powder according to the preceding claim, wherein said base particles have a sphericity index greater than 0.1 and less than 0.3. 7. Powder according to any one of claims 3 to 6, having a porosity index Ip greater than 5. 8. Powder according to the preceding claim, having a porosity index Ip greater than 10. The powder of any one of claims 3 to 8, wherein at least 80% by number of said base particles are needle and / or wafer shaped. 10. Powder according to the preceding claim, wherein at least 80% by number of said base particles are assembled in the form of ordered and / or disordered aggregated particles. 11. Powder according to the preceding claim, wherein said aggregated particles are in the form of stars having 3 to 15 branches. The powder of claim 10, wherein said aggregated particles are in the form of lamellae consisting of 2 to 50 platelets. The powder of claim 10, wherein said aggregated particles are in the form of hollow spheres having a sphericity index greater than 0.7 and having a central cavity such that, if D denotes the largest outside diameter of the particle and D 'denotes the largest inside diameter of the cavity, D / D' 2. 14. Powder according to any one of claims 3 to 13, wherein all the dimensions of the basic and / or aggregated particles are greater than 50 nm. 15. Powder according to the preceding claim, wherein all the dimensions of the basic and / or aggregated particles are greater than 200 nm. 16. Powder according to any one of claims 3 to 15, having a maximum particle size of the base and / or aggregated D99.5 less than 150 m. The powder according to any of the preceding claims, said hydrate being doped with a dopant selected from the compounds of elements of column 17, the compounds of elements of column 1, the compounds based on yttrium Y, Sc scandium, lanthanide, alkaline earth metal, Ti titanium, Si silicon, S sulfur, P phosphite, Al aluminum, Tungsten W, Cr chromium, Mo molybdenum, vanadium V, antimony Sb, nickel Ni, copper Cu, zinc Zn, iron Fe, manganese Mn, niobium Nb, gallium Ga, tin Sn, lead Pb, cobalt Co, ruthenium Ru, Rh rhodium, Pd palladium, Ag silver, Os osmium, Ir irium, Pt platinum, Au gold and mixtures thereof. 18. Powder according to the preceding claim, said hydrate, said first hydrate being doped by means of a dopant chosen from: a second hydrate of an element chosen from Y, La, Ce, Sc, Ca, Mg and mixtures thereof, in intimate molecular mixing with said first hydrate; an aluminum hydrate dispersed in said first hydrate; an oxide of an element selected from Si, S and mixtures thereof, dispersed in said first hydrate; - and their mixtures. 19. Powder according to any one of the two immediately preceding claims, the molar amount of dopant being less than or equal to 20%. 20. A device selected from a catalyst, a catalyst support, a filter element, a fuel cell element, a piezoelectric material, an optical connector, a dental ceramic, a structural ceramic, comprising or obtained from a powder according to any one of claims 3 to 19.