Abstract: The invention pertains to methods of producing aluminum trioxide in the form of powders or agglomerations with particles having a porous honeycomb structure, which can be used as catalyst substrates, adsorbents and filters for the chemical, food, and pharmaceutical industry. The method of production of aluminum oxide in the form of powders or agglomerations with particles having a porous honeycomb structure involves the treatment of the aluminum salt with a solution of an alkaline reagent, washing of the sediment and thermal treatment thereof. The technical result of the invention is the production of aluminum oxide in the form of separate particles with given structure and properties, specifically, with particle porosity of 60-80% and a porous structure represented by extensive parallel channels with near hexagonal packing, with dimension of the channels at the diameter of 0.3 to 1.0 micron and length up to 50 microns.

Abstract: A process for preparing a mesoporous alumina is described, comprising the following steps: a) mixing, in aqueous solution, at least one source of aluminum constituted by an aluminum alkoxide, at least one cationic surfactant and at least one organic solvent selected from methanol and ethanol; b) hydrothermally treating the mixture formed in said step a); c) drying the solid formed in said step b); d) calcining the solid formed in said step c).

Abstract: The present invention relates to a process for preparing boehmitic aluminas by hydrolysis of aluminum alcoholates in aqueous, alkaline solution. It further relates to aluminas or alumina hydrates prepared by this process and their uses.

Abstract: Process for the preparation of quasi-crystalline boehmite comprising the steps of: (a) preparing an aqueous precursor mixture comprising a water-insoluble aluminum source; (b) decreasing the pH of the precursor mixture of step (a) by at least 2 units; (c) increasing the pH of the mixture of step (b) by at least 2 units, and (d) aging the mixture of step (c) under hydrothermal conditions to form a quasi-crystalline boehmite. This process provides for the hydrothermal preparation of quasi-crystalline boehmites with high peptizability. The invention therefore further relates to quasi-crystalline boehmites with a high peptizability, measured as the Z-average submicron particle size. This Z-average submicron particle size preferably is less than 500 nm, more preferably less than 300 nm, even more preferably less than 200 nm, and most preferably less than 100 nm.

Abstract: The present invention refers to nanocrystalline spherical ceramic oxides, to the process for the synthesis and use thereof. These oxides, obtained by detonation of a water-in-oil emulsion (W/O), besides having a spherical morphology and nanocrystallinity, show a set of complementary features, namely a particle dimension inferior to 40 ?m, bimodal particle size distribution, high purity, deagglomeration and stable crystalline stages. This set of features makes these powders particularly suitable for several applications such as coating processes, near net shape processes and, when applied in ceramics industry, they provide dense and porous ceramic objects of exceptionally high mechanical resistance.

Abstract: The present invention discloses a continuous calcination vessel which can be used to prepare calcined chemically-treated solid oxides from solid oxides and chemically-treated solid oxides. A process for the continuous preparation of calcined chemically-treated solid oxides is also provided. Calcined chemically-treated solid oxides disclosed herein can be used in catalyst compositions for the polymerization of olefins.

Abstract: The invention relates to the field of catalyst supports presenting a pore volume having an at least bimodal distribution, thus defining a main porosity and a secondary porosity, the main porosity being of an average size greater than the secondary porosity.

Abstract: The present invention provides ?-alumina powders comprising ?-alumina particles of which at least 80% of the ?-alumina particles have a particle size of less than 100 nm. The invention also provides slurries, particularly aqueous slurries, which comprise ?-alumina powders of the invention. The invention further provides methods of manufacturing ?-alumina powders and ?-alumina slurries of the invention and methods of polishing using same.

Abstract: A process for the preparation of a catalyst, which process comprises the steps of: i) mixing an alumina precursor with combustible carbon-containing fibers with a diameter in the range of from 0.5 to 5 ?m and a length of no greater than 100 ?m in an amount in the range of from 20 to 40 wt % based on the total dry mixture; ii) adding nitric acid and water to form an extrudable mass; iii) extruding the mixture to form shaped particles; iv) drying the shaped particles; v) heating the particles in an atmosphere comprising no more than 5 vol % oxygen at a temperature in the range of from 350 to 600° C.; and vi) then heating the particles in a gas mixture comprising at least 12 vol % oxygen at a temperature in the range of from 450 to 600° C.

Abstract: The invention relates to a method for obtaining ?-alumina crystals or fibers using the vapor-liquid-solid (VLS) mechanism, by controlling the slightly oxidizing atmospheres in systems that contain metal Al and SiO2. The inventive method consists of growing ?-alumina fibers using the growth of alumina fibers via VLS from Al and SiO2, and controlling the partial pressure of the different oxidizing agents, in the area known as active oxidation of Al with formation of corundum fume and active oxidation of Si with formation of silica fume in accordance with the respective Si—SiO2 and Al—Al2O3 volatility diagrams.

Abstract: Multi-step metal compound oxidation process to produce compounds and enhanced metal oxides from various source materials, e.g. metal sulfides, carbides, nitrides and other metal containing materials with metal oxides from secondary reaction steps being utilized as an oxidation agent in the first reactions.

Abstract: The present invention provides ?-alumina powders comprising ?-alumina particles of which at least 80% of the ?-alumina particles have a particle size of less than 100 nm. The invention also provides slurries, particularly aqueous slurries, which comprise ?-alumina powders of the invention. The invention further provides methods of manufacturing ?-alumina powders and ?-alumina slurries of the invention and methods of polishing using same.

Abstract: A method for producing an ?-alumina powder is described. The method for producing an ?-alumina powder comprises a step of calcining an aluminum salt in the presence of a seed crystal at 600-890° C.

Abstract: Disclosed is a process for preparing fine metal oxide particles, comprising the following steps of reacting a reactant mixture comprising i) water, ii) at least one water-soluble metal nitrate and iii) ammonia or ammonium salt at 250–700° C. under 180–550 bar for 0.01 sec to 10 min in a reaction zone to synthesize the metal oxide particles, the metal nitrate being contained at an amount of 0.01–20 wt % in the reactant mixture; and separating and recovering the metal oxide particles from the resulting reaction products. According to the present invention, nano-sized metal oxide particles are synthesized, while the harmful by-products generated concurrently therewith are effectively decomposed in the same reactor.

Abstract: Mesoporous crystalline alumina compositions and process for the preparation thereof are described. The compositions are useful as catalysts and absorbents.

Abstract: A method for producing ?-alumina powder is described. The method comprises the steps of removing water from a compound containing the following (1), (2), (3) and (4), and calcining the results: (1) ?-alumina precursor, (2) seed crystal, (3) water, (4) nitrate ion in an amount of from 2.8 to 3.3 mol per mol of aluminum (Al) contained in the ?-alumina precursor and the seed crystal.

Abstract: The present invention relates to a single step process for the synthesis of nanoparticles of phase pure ceramic oxides of a single or a multi-component system comprising one or more metal ions. The process comprises preparing a solution containing all the required metal ions in stoichiometric ratio by dissolving their respective soluble salts in an organic solvent or in water, preparing a precursor, adjusting the nitrate/ammonia content in the system, and heating the system.

Abstract: A catalyst for hydrofining fraction oils, comprises an alumina carrier and at least one metal and/or thereof oxide of Group VIB and at least one metal and/or thereof oxide of Group VIII supported on said alumina carrier. The pore volume of said alumina carrier is not less than 0.35 ml/g, in which the pore volume of the pores having a diameter of 40-100 angstrom accounts for more than 80% of the total pore volume, the alumina carrier is prepared by a special process. The catalyst possesses relatively high hydrogenation activity.

Abstract: The invention concerns a process for synthesising aluminas with a controlled porosity in which the pore diameter is in the range 0.6 nm to 80 nm. This process is carried out in a plurality of steps including at least one step a) in which an alumina precursor is prepared by hydrolysis of at least one anionic inorganic source of aluminium in the presence of at least one surfactant. Step a) of the process is carried out in an essentially aqueous medium the pH of which is generally higher than the isoelectric point of the alumina. The process of the invention also comprises at least one step b) in which the precipitate obtained is dried in air at a temperature of about 40° C. to 110° C. for a period of about 2 to 30 hours, and at least one step c) in which the dried precipitate is calcined at a temperature which is sufficient to eliminate the molecules of surfactant present in the precursor.

Abstract: A method for preparing an oxide (P), which includes the steps of (i) forming a solid phase compound (O) based on an oxide containing molecular entities (1) chosen from optionally substituted ammonium, diammonium, diazan-ium or diazandium, the entities being distributed within the solid matrix, and (ii) eliminating the entities (1) from the solid phase compound (O) by reacting the solid phase compound (O) with a gaseous stream containing a break-down reactant for the entities (1), and isolating the resulting solid material (P).

Abstract: Gamma-aluminum oxynitride ground powders, white in color and well suited for conversion into optically transparent ceramic shaped articles, 100% of the particles of which being less than 10 .mu.m in size and exhibiting a transmittance of at least 8%, are prepared by grinding particulate gamma-aluminum oxynitride agglomerates having a porosity of greater than 75%, such agglomerates themselves being produced by interreacting dry powdery admixture of aluminum nitride, alpha-alumina, and an alumina of high specific surface area or precursor thereof.

Abstract: An aqueous slurry of about 100-1000 centipoises viscosity suspending about 200-2000 g/l of aluminum hydroxide particles smaller than 5 .mu.m is spray-dried, and the dried powders are calcined to obtain alumina powders. The alumina powders have a sharp particle size distribution, being suitable for electronic, abrasive and refractory applications.

Abstract: Aluminum oxynitride is prepared by the pyrolysis of an organosiloxydihaloalane such as trimethylsiloxydichloroalane in the presence of a nitrogen-containing atmosphere. The organosiloxydihaloalane may conveniently be prepared by reacting together an aluminum halide and at least one disiloxane.

Abstract: A novel process is described for the preparation of monodisperse ceramic ders wherein particulate oxides or hydroxides are obtained by reaction of hydrolysable compounds with water. The reaction is carried out in the presence of a complexing agent and, optionally, a stabilizer.

Abstract: Zirconium-doped pseudoboehmite with the following properties: zirconium content of 0.5 to 10 mol % relative to Al water content of 20 to 35 weight percent total of the anionic impurities less than 0.5 weight percent. It is synthesized by a process wherein zirconium salt is added in calculated quantity to an aqueous aluminum sulfate solution, the resulting mixture is fed simultaneously with a sodium aluminate liquor into a water pool having a temperature of 50.degree. to 100.degree. C., thereby precipitating zirconium-doped alumina gel while a pH of 3.5 to 8 is maintained, the pH of the suspension is adjusted after addition of the aluminum sulfate solution to 8.5 to 10.5 by further addition of sodium aluminate liquor, the suspension is digested if necessary at the pH of 8.5 to 10.5 and the temperature of 50.degree. to 100.degree. C. for a period of up to 24 hours, the formed pseudoboehmite crystals are filtered off, the filter cake is redispersed with water and the suspension is sprayed-dried.

Abstract: The present invention includes metal oxide foam particles and a method of making the same. A decomposable metal salt feed solution is injected into a hot atomizing gas. The mixture of hot atomizing gas and feed solution is maintained in the reactor until the feed solution converts to metal oxide foam particles. The metal oxide foam particles have a high specific surface area.

Abstract: The process for the manufacture of special aluminas from the powder produced in the calcination of alumina hydrate, as proposed by the invention, achieves the recovery of this by-product, treating it separatedly from the rest of the alumina, in order to convert it into special alumina of high calcination degree, or alpha alumina, being adequate for uses other than aluminum production. The process is carried out by submitting the by-product to a water-washing stage that reduces its sodium content, solid and liquid separation, filtering and drying. A drying operation is finally carried out with a calcination at a high temperature wherein the alumina of high calcination degree is transformed into alpha alumina.

Abstract: An article of manufacture is provided comprising a polycrystalline cubic aluminum oxynitride having a density of at least 98% of theoretical density, and being transparent to electromagnetic radiation in the wavelength range from 0.3 to 5 micrometers with an in-line transmission of at least 20% in this range.A method of preparing the optically transparent aluminum oxynitride is also provided comprising the steps of forming a green body of substantially homogeneous aluminum oxynitride powder and pressureless sintering said green body in a nitrogen atmosphere and in the presence of predetermined additives which enhance the sintering process. Preferred additives are boron and yttrium in elemental or compound form.

Abstract: High surface area, wide-pore-containing porous alumina are prepared by mulling together alumina hydrogel and alpha alumina monohydrate, extruding, drying and calcining at 500.degree.-700.degree. C.

Abstract: High surface area, wide-pore-containing porous aluminas are prepared by mulling together aluminum nitrate derived hydrogels with sodium aluminate derived hydrogels, extruding, drying and calcining at 500.degree.-700.degree. C.

Abstract: An improved method of preparing alumina, including a first stage in which an alumina hydrogel is formed from seed aluminum hydroxide, and a second stage in which the alumina hydrogel is processed for conversion into alumina.

Abstract: An improved process for the preparation of alumina, including forming an alumina hydrogel from aluminum hydroxide, and processing the alumina hydrogel into alumina. The improvement involves the alumina hydrogel forming step which is connected in the presence of sulfate ion and which comprises providing, in a reaction zone, an aqueous slurry containing seed aluminum hydroxide and having a pH of 6-11, and feeding to the reaction zone an aluminum compound and a pH controlling agent for mixing with the aqueous slurry while maintaining the aqueous slurry at a temperature of at least about 50.degree. C. at feed rates so that the pH of the aqueous slurry is maintained within the range of 6-11 and that 0.2-5 mols/hour of aluminum components, in terms of elemental aluminum, are fed to the reaction zone per mole of the seed aluminum hydroxide originally contained in the aqueous slurry, whereby the seed aluminum hydroxide is caused to grow to the aluminum hydrogel.

Abstract: Hydrargillite is converted into boehmite by preparing a suspension (A) of hydrargillite in water with a proportion from 150 g/l to 700 g/l of dry material expressed as Al.sub.2 O.sub.3, subjecting it to heat treatment under pressure (D) at a temperature of from 200.degree. C. to 270.degree. C., the speed of the rise in temperature of said suspension being at least 1.degree. C./minute, and causing it to pass a period of time of from 1 minute to 60 minutes in a holding zone (D) at a temperature in the range of from 200.degree. C. to 270.degree. C.The boehmite produced has a granulometry which is at most identical to that of the initial hydrargillite, and has a much lower content of alkaline material.

Abstract: Processes for the preparation of pure alumina powders or pure non-stoichiometric alumina-magnesia spinel powders starting with ammonium alum-based compositions which are dehydrated, the dehydration being carried out on dehydrated salts having a bulk density less than 0.2 kg/dm.sup.3 and wherein the dehydration is followed by a calcination with a heating schedule containing at least one intermediate stage at 750.degree. to 850.degree. C., the process of the invention permitting the reproducible production of such aluminas or spinels having specific surfaces of from 100 to 200 m.sup.2 /g and characterized by a very high homogeneity which guarantees a rigorously unimodal pore structure, such aluminas and spinels being useful in preparing isotopic enrichment barriers for gaseous diffusion, as well as metal polishes, catalysts, and catalyst supports.

Abstract: An article of manufacture is provided comprising a polycrystalline cubic aluminum oxynitride having a density of at least 98% of theoretical density, and being transparent to electromagnetic radiation in the wavelength range from 0.3 to 5 micrometers with an in-line transmission of at least 20% in this range.A method of preparing the optically transparent aluminum oxynitride is also provided comprising the steps of forming a green body of substantially homogeneous aluminum oxynitride powder and pressureless sintering said green body in a nitrogen atmosphere and in the presence of predetermined additives which enhance the sintering process. Preferred additives are boron and yttrium in elemental or compound form.

Abstract: Ultrapure and homogeneous boehmites and/or pseudo-boehmites, suitable, whether before or after drying and/or calcination, as, e.g., fillers, binders, thickeners, dispersing agents, and the like, are prepared (i) by admixing an amorphous aluminum hydroxycarbonate, itself advantageously prepared by carbonating an alkali metal aluminate with carbon dioxide and then filtering and washing the precipitate which results, with a solution of an acid, a base, a salt, or mixture thereof, with the pH of the resulting reaction medium being maintained at a value of less than 11, (ii) next heating such reaction medium at a temperature of less than 90.degree. C. for a period of at least 5 minutes, and (iii) then heating the reaction medium resulting from the step (ii) at a temperature ranging from 90.degree. C. to 250.degree. C.

Abstract: A method of manufacturing spherical alumina particles which comprises the steps of digesting, at an elevated temperature and an elevated pressure, gibbsite with an aqueous hydrochloric acid solution and then forming an aqueous basic aluminum chloride solution; adding, at an elevated temperature, an aqueous ammonia to said aqueous basic aluminum chloride solution to form an alumina hydrosol containing ammonium chloride; commingling said alumina hydrosol with a gelling agent; thereafter dispersing droplets of said mixture in a suspending medium under conditions effective to transform said droplets into hydrogel particles; ageing said hydrogel particles first in said suspending medium and then in aqueous ammonia; and then washing said hydrogel particles with water, drying and calcining to obtain spherical alumina particles.

Abstract: Process for preparing high purity aluminas from ammonium alum, the process comprising separately dehydrating the alum and thereafter thermally decomposing the dehydrate, wherein the thermal decomposition is carried out by forcing a gas through a layer of the dehydrated alum so as to continuously remove the gaseous reaction products formed without removal of solids by the carrier gas, and providing improved productivity of high purity transition aluminas having specific surfaces above 125 m.sup.2 /g and/or bulk densities above 0.2 g/cm.sup.3, the transition aluminas so obtained being characterized by their greater reactivity for the preparation of corundum so that corundum having a bulk density greater than 0.4 g/cm.sup.3 can be economically prepared.

Abstract: Aqueous suspensions of alumina particulates, at least a portion of which comprising ultrafine boehmite, are prepared by maintaining a pH<9 aqueous formulation of poorly crystallized and/or amorphous activated alumina powder for such period of time as to effect the at least partial transformation of such alumina powder into ultrafine boehmite.

Abstract: A pseudoboehmite having properties suitable for incorporation into a matrix for a zeolite containing catalyst and the process for producing the same from an aluminum sulfate derived gel.

Abstract: The process relates to the preparation of a shaped body having at least one dimension less than 100 microns and comprising alumina or an alumina hydrate. An aqueous composition comprising a water-soluble aluminum compound, for example aluminum chloride, sulphate, acetate, formate, propionate, oxalate, phosphate or nitrate and a water-soluble organic polymer is formed into the desired shape. The body so formed is dried, and is subjected to hydrothermal treatment at a temperature of at least 200.degree. C. to decompose the aluminum compound to alumina or an alumina hydrate. The body is optionally further heated subsequent to the hydrothermal treatment.

Abstract: An alumina particle and a method of its manufacture. The alumina particle comprises a spheroidal alumina particle of about 1/16 inch in diameter and a crush strength of from about 13 to about 16 pounds. The method comprises preparing a mixture of an acidic alumina hydrosol and an ammonia percursor at below gelation temperature, dispersing the mixture as droplets in a water-immiscible liquid at a temperature and for a time to effect at least partial gelation of the hydrosol to form hydrogel particles, contacting the hydrogel particles with a liquid having a pH no greater than about 7 and an osmotic pressure sufficient to prevent disintegration of the hydrogel particles, aging the hydrogel particles in an aqueous solution having a pH greater than 7, and thereafter drying and calcining the hydrogel particles.

Abstract: Method of producing pseudoboehmite by reacting an aluminum salt with an aluminate.

Abstract: A catalyst carrier comprising gamma alumina wherein the apparent bulk density is in the range of from 0.65 g/cc to 0.71 g/cc, the total pore volume is in the range of from 0.55 cc/g to 0.65 cc/g, the content of pores having a diameter in the range of from 60A to 110A occupies at least 75% of the total pore volume, the surface area is in the range of from 210 m.sup.2 /g to 250 m.sup.2 /g and the attrition loss is less than 0.5 wt. %. This sort of catalyst carrier can be namufactured through a series of steps of: (a) preparing a first alumina hydrosol having an aluminum concentration in the range of from 9.8 wt. % to 14.4 wt. % and a weight ratio of aluminum to chloride in the range of from 0.95 to 1.20, (b) preparing a second alumina hydrosol having an aluminum concentration in the range of from 9.5 wt. % to 13.0 wt. % and a weight ratio of aluminum to chloride in the range of from 0.85 to 0.

Abstract: The production process for pseudoboehmite from leach liquors produced in the acid treatment of clays, which liquors contain Fe and alkaline earth ions.

Abstract: The invention relates to a new highly reactive alumina and the method of preparing it. The alumina is characterized by an amorphous structure and a specific surface of greater than 600 m.sup.2 /g. It is prepared by thermal decomposition of the double carbonate of aluminum and ammonium of the formula AlNH.sub.4 CO.sub.3 (OH).sub.2 at a temperature of between about 200.degree. and 500.degree. C.Aluminum hydroxychlorides of the formula Al.sub.2 (OH).sub.x Cl.sub.6-x can be prepared from it.

Abstract: Aluminum nitrate solutions are subjected to hydrolysis at elevated temperature and pressure, with the pressure being kept relatively low by continual bleeding of reactant gases from the reaction vessel. The resultant product is a noncrystalline alumina that may be readily converted to crystalline alumina by roasting.In addition, the discharged reactant gases are employed for leaching of clay to provide aluminum nitrate feed solution.

Abstract: AlCl.sub.3.6H.sub.2 O is decomposed at a temperature above about 700.degree. C. in the presence of hydrogen to form an alumina product having a very low residual chlorine content.

Abstract: Improved .gamma.-alumina suitable for use as a catalyst carrier having high mechanical strength, a large specific surface area, and a substantially uniform pore size distribution in a relatively small portion of the pore size range below 500 A. Said alumina is produced by first establishing a seed aluminum hydroxide hydrogel having a pH of between 6 and 10 and then repetitively and sequentially adding an aluminum compound to adjust the pH to less than 5 or more than 11 to dissolve crystallites of aluminum hydroxide followed by addition of a neutralizing agent to return the hydrogel to the pH range from about 6 to 10 to cause pseudo-boehmite crystallites to grow. After a sufficient number of repetitions of said sequential addition, sparse aggregates of crystallites of the desired structure are formed. These are dried and calcined to produce the said alumina.

Abstract: A structural ceramic material comprising single phase polycrystalline cubic aluminum oxynitride preferably with at least 97% of theoretical density which displays transparency and isotropic optical, thermal and electrical properties, an infrared cutoff at about 5.2 microns wavelength, and which shows no chemical or physical property change after heating in air (atmosphere) at 1100.degree. C.