Abstract: A ?-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate ?-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated ?-alumina.

Abstract: A method of synthesizing metal alkoxide polymers is provided, for use, as an example, in synthesizing hybrid organic/inorganic materials with low optical absorption for optical applications. The method involves a plurality of acidolysis steps involving acidolysis of a metal alkoxide compound with an acid to produce an intermediate acidolysed solution, and combining and condensing the intermediate acidolysed solutions to produce the metal alkoxide polymer.

Abstract: Disclosed are a porous material comprising particles without substantial fibrous structure and having pores, the pores having a mean pore diameter in a meson-pore region, sharp pore size distribution, and at least a part of the pores being connected three-dimensionally to form a three-dimensional network structure with random passages, the porous material preferably being of alumina and having a spongy structure or the porous material preferably being an aggregate of particles having an aspect ratio of 3 or less; a process of producing the porous material which includes a step of aging a system capable of becoming an oxide on thermal decomposition; a catalyst for exhaust gas purification having excellent NOx removal performance, high resistance against sulfur poisoning, and satisfactory high-temperature durability which comprises the porous material as a carrier having supported thereon a noble metal and an NOx storage component; and a method of exhaust gas purification using the catalyst.

Abstract: Disclosed is a process for preparing an alumina composition having high specific surface area and large pore volume, comprising preparing a reaction mixture having a given molar ratio between a monobasic acid and water by the use of an aluminum source such as acid-containing alumina obtained by heat treatment of aluminum hydroxide in the presence of an acid, bayerite, ?-alumina and ?-alumina, optionally adding an oxygen-containing organic compound or an inorganic polybasic acid as a pore structure controlling agent, performing sol-forming reaction, and then subjecting the product obtained by the sol-forming reaction to an appropriate operation such as alkali addition or heat dehydration treatment.

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 method of making a concentrated, stable aluminum compound containing water treatment product comprising reacting an aluminum compound in solution form with a phosphoric acid compound at a temperature in the range of about 15° C. to about 98° C., measuring the aluminum as aluminum oxide content and adding water to the reaction product if needed to prepare a product having an aluminum oxide content of about 10 percent by weight of the solution. The process is particularly advantageous in providing a system for the production of aluminum water treating products by recycling aluminum waste metal such as beverage containers utilizing a phosphoric acid medium.

Abstract: A catalyst support having improved attrition resistance and a catalyst produced therefrom. The catalyst support is produced by a method comprising the step of treating calcined &ggr;-alumina having no catalytic material added thereto with an acidic aqueous solution having an acidity level effective for increasing the attrition resistance of the calcined &ggr;-alumina.

Abstract: A method for making alumina having a pore structure characterized by the absence of macropores, no more than 5% of the total pore volume in pores greater than 350 Å, a high pore volume (greater than 0.8 cc/g measured by mercury intrusion) and a bi-modal pore volume distribution character, where the two modes are separated by 10 to 200 Å, and the primary pore mode is larger than the median pore diameter (MPD), calculated either by volume or by surface area, the MPD by volume being itself larger than the MPD by surface area. Alumina made by such process and catalyst made therefrom.

Abstract: A process for the production of alumina is performed by dissolving gibbsite Al2O3.3H2O in nitric acid to provide an acid solution containing aluminum nitrate; decomposing the acid solution at 300-700° C. with a free air supply to form alumina and Nox by spraying onto the inner surface of one or more rotary kilns, drying in a fluid bed, or drying in a steel belt conveyor furnace; regenerating the formed NOx into concentrated nitric acid and recycling the nitric acid to be used for the dissolving of gibbsite; and recovering the alumina formed upon decomposing the acid solution.

Abstract: A method for making &ggr;-alumina includes drying wet alumina gels at temperatures and pressure below those commonly present in preparation of &ggr;-alumina. The method allows for production of &ggr;-alumina with greater ease of production and controllability of physical properties than known methods. Alumina produced using this method has high surface area and porosity and is highly suitable for making &ggr;-alumina powders for use as catalyst supports.

Abstract: A modified alumina is useful as metals passivator in fluidizable catalytic cracking catalysts. The modified alumina is prepared from a hydrated alumina, e.g., gibbsite, which is reacted with a low-molecular weight organic acid, e.g., acetic acid, forming aluminum salts. Calcination of the modified alumina results in decomposition of the aluminum salt.

Abstract: Aluminum polychlorosulphates having the general formula (I) Al(OH)l Clm(SO4)nMp(I) where M represents an alkali metal l, m, n, p represent the number of moles per mole of aluminum, so that 1.74≦l≦2.25, 0.01≦n≦0.17, 0.32≦p≦1.49, and l+m+2n=p+3, their use as coagulation and flocculation agents, and their preparation process by reaction, at room temperature, of an alkali metal basic compound, such as Na2CO3, NaHCO3, NaOH, K2CO3, KHCO3 and KOH, and an alkali metal sulphate or sulphuric acid with an aluminum polychloride or polychlorosulphate having the general formula(I′) Al(OH)l′Clm′(SO4)n′Mp′(I′) where 1.1≦1′≦1.44, n′≦0.10, p′<p(p of formula (I)), and l′+m′+2n′=p′+3.

Abstract: Disclosed is a process for preparing an alumina composition having high specific surface area and large pore volume, comprising preparing a reaction mixture having a given molar ratio between a monobasic acid and water by the use of an aluminum source such as acid-containing alumina obtained by heat treatment of aluminum hydroxide in the presence of an acid, bayerite, &rgr;-alumina and &ggr;-alumina, optionally adding an oxygen-containing organic compound or an inorganic polybasic acid as a pore structure controlling agent, performing sol-forming reaction, and then subjecting the product obtained by the sol-forming reaction to an appropriate operation such as alkali addition or heat dehydration treatment.

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: Disclosed are a porous material comprising particles without substantial fibrous structure and having pores, the pores having a mean pore diameter in a meso-pore region, sharp pore size distribution, and at least a part of the pores being connected three-dimensionally to form a three-dimensional network structure with random passages, the porous material preferably being of alumina and having a spongy structure or the porous material preferably being an aggregate of particles having an aspect ratio of 3 or less; a process of producing the porous material which includes a step of aging a system capable of becoming an oxide on thermal decomposition; a catalyst for exhaust gas purification having excellent NOx removal performance, high resistance against sulfur poisoning, and satisfactory high-temperature durability which comprises the porous material as a carrier having supported thereon a noble metal and an NOx storage component; and a method of exhaust gas purification using the catalyst.

Abstract: &agr;-Alumina powder of fine particles having the primary particle diameters of from 10 nm to 100 nm, and of a high ratio of &agr;-phase and further having capability to provide a sintered body with high density, and a method of manufacturing the &agr;-alumina powder is provided. The method for manufacturing the &agr;-alumina powder comprises a step of mixing an aluminum compound which is the precursor for the corresponding &agr;-alumina and at least one selected from the group consisting of a titanium compound, an iron compound, a chromium compound, and &agr;-alumina, and aluminum nitride, aluminum carbide and a aluminum boride as a seed crystal(s), and a step of calcining the mixture at a temperature of from 600° C. to 1000° C. in the presence of HCl gas in an concentration of 1% by volume to 20% by volume.

Abstract: An admixture of hydrated alumina and an organic acid surfactant is calcined in an oxygen-depleted atmosphere, cooled before exposing it to air, comminuted and then centrifuged to produce nanometer-grade superfine &agr;-alumina powder.

Abstract: Pseudo-boehmite, which is a raw material for a catalyst carrier for hydrogenation refining, is produced by mixing, under a predetermined condition, an aluminate aqueous solution produced from an alkaline etching step for aluminum in an alumite treatment and an acidic aluminum aqueous solution produced from an anodization step for aluminum in the alumite treatment. Pseudo-boehmite can be also produced by maturing, with an alkaline solution, an aluminum hydroxide sludge produced from a washing step for aluminum in the alumite treatment. It is possible to establish a method for producing pseudo-boehmite, which makes it possible to reutilize a resource at extremely low cost by utilizing a treatment waste liquid and a sludge in an alumite treatment site.

Abstract: Ceramic honeycombs incorporating cell walls of a sintered alumina material providing controlled pore size distribution in combination with high BET surface area and flexural (MOR) strength are formed by the extrusion, drying and firing of plasticized alumina powder batches containing major proportions of anhydrous, high-surface-area gamma alumina powders dispersed with selected acids; low combined drying and firing shrinkages provide strong, crack-free bodies of high surface area and strength.

Abstract: Vanadium dioxide particles having formula V1−xMxO2, wherein 0≦x≧0.05 and M is a doping metal, and being characterized in that they have a particle size of less than 10 &mgr;m, a method for preparing same, and the use of said microparticles, in particular for surface coating, are disclosed.

Abstract: Disclosed herein is a recording medium comprising an alumina hydrate having an average pore radius of 20 to 200 Å and a half breadth of pore radius distribution of 20 to 150 Å.

Abstract: A process for the production of alumina comprising:

Abstract: A material with high surface area can be obtained through the partial or total removal of CaO and MgO by acid leaching of blast furnace slag. This is accomplished by an improved process for selective leaching of blast furnace slag and other solid solution materials by control of temperature during leaching, rate of addition of acid, type of the acid, concentration of the acid, and concentration of the slag in the slurry. When these variables are controlled as disclosed a hierarchy of dissolution occurs. The hierarchy begins with MgO, progresses to CaO, and is followed by A12O3, and the rate of acid addition is slow and controlled so that alumina does not dissolve (thereby depriving the remaining silica has no acid sites or catalytic activity). By invoking the hierarchy one gains selectivity, and this can be used to convert blast furnace slag to a material with high surface area which may have applications as an absorbent could be economically feasible.

Abstract: The smelting of aluminum from alumina in the Hall-Heroult process can be dramatically improved by lowering power consumption and in the use of carbon free anodes by using a feed of positively charged alumina. Laboratory experiments have shown that the apparent solubility and reactivity of alumina in molten fluoride baths is surprisingly increased by altering the negatively charged aluminum hydroxide Al(OH)4− particles, at about pH of nine, to positively charged particles containing Al+++ with a pH of less than two, by using acid solutions. The alumina thus produced is referred to as Al+++ alumina, or positively charged alumina. In particular, sulfuric acid is used to convert aluminum hydroxide using the Bayer process to a family of basic aluminum sulfates, 3Al2O3.4SO3.9H2O, which are dehydrated and calcined to produce Al+++ alumina.

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 catalyst for hydrodemetalization of heavy oil, especially residuum oil, and a process for preparing the same, wherein said catalyst comprises the metal elements of Groups VIII and/or VIB as active components supported on an alumina carrier having large pores. The total pore volume of said carrier is in the range of 0.80˜1.20 ml/g (by mercury porosimetry method), the specific surface area in the range of 110˜200 m2/g, the peak pore diameter in the range of 15˜20 nm, and the bulk density in the range of 0.50˜0.60 g/ml. In the process of the invention, a physical pore-enlarging agent and a chemical pore-enlarging agent are added simultaneously during the mixing of the pseudoboehmite to a plastic mass, then extruding, drying, calcining, the carrier is obtained, then impregnating with active components by spraying onto the carrier, after drying and calcining, the catalyst is obtained.

Abstract: Alpha alumina particles are made by heating particles of alumina with an aqueous solution containing a dissolved fluorine-containing compound and an acid; separating the particles from the solution and then calcining the particles at a temperature not greater than about 1025° C. The alumina particles preferably have an LOI in the range of about 1-20 wt. %; more preferably about 1-6 wt. %. Alpha alumina particles of the invention are more readily ground into smaller particles than alpha alumina particles made by calcining at higher temperatures. The remaining soda in the alpha alumina is found to be highly soluble in hot water. The process produces low soda content (0.01 wt. % Na2O or less) alpha alumina crystals from alumina feedstocks with 0.5 wt. % or more initial soda levels. The alpha alumina crystals produced are as large as 30-40 microns. Most typically; the size range is between 2 and 8 microns.

Abstract: Alumina particles having high dispersibility and plasticity, at least on the surface of which a phosphoric acid or phosphate is present and suitable for use as a material for pigments for paints, precision abrasives or ceramics. The alumina particles are produced by adding a crystallization inhibitor containing at least phosphate ion to aluminum hydroxide or alumina hydrate and then conducting a hydrothermal synthesis treatment. The amount of the phosphate ion to be added is in the range of 3.0×10−3 to 2.5×10−2 mol per mol of aluminum hydroxide or alumina hydrate. The particle size of aluminum hydroxide or alumina hydrate is 0.1 to 5.0 &mgr;m. The hydrothermal synthesis is preferably conducted at 350° C. or above under a pressure of 50 to 200 atm and at a temperature elevation rate of 5° C./min to 0.3° C./min. The thus obtained alumina is &agr;-alumina in the form of hexagonal plate single crystal having a particle size of 0.

Abstract: In order to produce aluminium oxide beads, an acid aluminium oxide sol or an acid aluminium oxide suspension is converted into droplets by a vibrating nozzle plate and pre-solidified after the formation of a bead shape by laterally blowing gaseous ammonia and then coagulated in an ammonia solution.

Abstract: An alumina sol, containing a small amount of water of crystallization inside the crystal lattice of boehmite, having high mechanical strength, properties suitable for use as an alumina adsorbent or carrier, and the ability to be formed without additional concentration. The alumina sol comprises a fibrous boehmite having the molecular formula Al2O3.1.05-1.30 H2O with the weight average diameter and the weight average length being respectively in the range of 3 to 50 nm and in the range of 30 to 3000 nm, and has an alumina concentration of 15 to 60% by weight.

Abstract: A fire-retardant plastic mixture contains 55%-75% by weight of boehmite which has an orthorhombic crystal structure and has the general formula AlO.sub.x (OH).sub.3-2x with x-values ranging between 0.8 and 0.99, and has a mean grain diameter d.sub.50 ranging between 0.4 and 0.7 .mu.m, a d.sub.10 value ranging between 0.7 and 1.2 .mu.m and a d.sub.90 value ranging between 0.2 and 0.4 .mu.m. The filler material is used in the form of a finely-crystallized hydrargillite which is obtained during a precipitation process according to Bayer with a grain diameter of 0.5 to 3 .mu.m, which is suspended and which, without any mechanical working, is transformed directly in a hydro-thermal process at temperatures ranging between 220.degree. C. and 240.degree. C. under turbulent conditions into a boehmite of the general formula AlO.sub.x (OH).sub.3-2x with x-values ranging between 0.8 and 0.99.

Abstract: Aluminum hydroxide is disclosed, wherein a mean particle size of a secondary particle is from 0.1 to 8 .mu.m, a BET specific surface area is not less than about 30 m.sup.2 /g and a pore size distribution has a maximum value within the range from 5 to 100 nm, a method for producing the same, and a method of using the same, comprising containing the same in a rubber, a method for using the same as a filler of a rubber composition for tire tread, and a rubber composition for tire tread using the same.

Abstract: Provided is a process for preparing alumina agglomerates which comprises:(i) treating agglomerates of active alumina with an aqueous medium comprising at least one acid making it possible to dissolve at least part of the alumina and at least one compound providing an anion capable of combining with aluminum ions in solution,(ii) subjecting the agglomerates to a hydrothermal treatment at a temperature in the range of from about 80.degree. C. to about 250.degree. C., and then(iii) thermally activating the agglomerates at a temperature in the range of about 500.degree. C. to about 1100.degree. C.The resulting alumina agglomerates possess exceptional mechanical strength, heat resistance and hydrothermal resistance and are useful as catalysts or catalyst supports.

Abstract: A process for producing alumina hydrates having a boehmite structure is provided. These alumina hydrates are dispersible in water. The boehmite or pseudoboehmite in colloids having a pH value of between 3 and 7 is present in a nanocrystalline form (<4 nm) whereby an exceptionally high translucence is imparted to the colloid.

Abstract: Alumina particles having high dispersibility and plasticity, at least on the surface of which a phosphoric acid or phosphate is present and suitable for use as a material for pigments for paints, precision abrasives or ceramics. The alumina particles are produced by adding a crystallization inhibitor containing at least phosphate ion to aluminum hydroxide or alumina hydrate and then conducting a hydrothermal synthesis treatment. The amount of the phosphate ion to be added is in the range of 3.0.times.10.sup.-3 to 2.5.times.10.sup.-2 mol per mol of aluminum hydroxide or alumina hydrate. The particle size of aluminum hydroxide or alumina hydrate is 0.1 to 5.0 .mu.m. The hydrothermal synthesis is preferably conducted at 350.degree. C. or above under a pressure of 50 to 200 atm and at a temperature elevation rate of 50.degree. C./min to 0.3.degree. C./min. The thus obtained alumina is .alpha.-alumina in the form of hexagonal plate single crystal having a particle size of 0.2 to 15 .mu.

Abstract: A process for the simultaneous recovery of substantially pure alumina and silica from an aluminosilicate. The process comprises the following steps: (i) heating the aluminosilicate with hydrated CaCl.sub.2 to obtain calcium-alumino-silicate and calcium-aluminate products, wherein the CaCl.sub.2 is substantially free of MgCl.sub.2 ; (ii) leaching the products with HCl to form a solution comprising AlCl.sub.3 and CaCl.sub.2, and insoluble silica; (iii) separating the insoluble silica from the solution; and (iv) crystallizing AlCl.sub.3 from the solution and recovering the alumina from the crystallized AlCl.sub.3. The process may further comprise the following steps: (v) substantially removing MgCl.sub.2 from the CaCl.sub.2 solution of step (iv); and (vi) recycling the CaCl.sub.2 solution for use in step (i).

Abstract: A process for producing a stable acidic aqueous alumina sol containing 50 to 300 nm of elongate secondary particles which are elongated in only one plane and formed by edge-to-edge coagulation of rectangular plate-like primary particles having a length of one side of 10 to 30 nm when observed through an electron microscope, the process comprises the steps of:(A) adding an alkali to an aqueous alumina sol containing fibrous colloidal particles of an amorphous alumina hydrate to produce a reaction mixture having a pH of 9 to 12,(B) subjecting the reaction mixture obtained in the step (A) to a hydrothermal treatment at a temperature of 110 to 250.degree. C. to produce an aqueous suspension containing an alumina hydrate having a boehmite structure, and(C) desalting the aqueous suspension obtained in the step (B) by adding water and an acid by ultrafiltration to form an acidic aqueous alumina sol having a pH of 3 to 6.

Abstract: This invention relates to a process for producing an enhanced adsorbent particle comprising contacting a non-amorphous, non-ceramic, crystalline, porous, calcined, aluminum oxide particle that was produced by calcining at a particle temperature of from 400.degree. C. to 700.degree. C., with an acid for a sufficient time to increase the adsorbent properties of the particle. A process for producing an enhanced adsorbent particle comprising contacting a non-ceramic, porous, oxide adsorbent particle with an acid for a sufficient time to increase the adsorbent properties of the particle is also disclosed. Particles made by the process of the instant invention and particle uses, such as remediation of waste streams, are also provided.

Abstract: The invention relates to a method for producing an adsorbent and/or catalyst and binder system comprising I) mixing components comprising (a) a binder comprising a colloidal metal oxide or colloidal metalloid oxide, (b) an oxide adsorbent and/or catalyst particle, and (c) an acid, (ii) removing a sufficient amount of water from the mixture to cross-link components a and b to form an adsorbent and/or catalyst and binder system. The invention also relates to particles made by the process, binders, and methods for remediating contaminants in a stream.

Abstract: The invention concerns a process for the production of alumina for ceramics by calcining alumina trihydrate in the presence of a mineralizer such as a halogenated compound and/or a boron compound, the calcined alumina being constituted by friable agglomerates of elementary particles, or crystallites, of alpha alumina, the average size of which can be fixed as required, with a unimodal narrow distribution of crystallite sizes, characterized in that calcining of the alumina trihydrate is carried out in an industrial kiln in a renewed oxidising atmosphere at a temperature in the range 800.degree. C. to 1300.degree. C. for a period of 0.5 hour to 4 hours in the simultaneous presence of a halogenated compound acting as a mineralizer and a silica based alumina recrystallisation modifier which is uniformly and intimately distributed in the alumina trihydrate charge.

Abstract: An alumina sintered body containing, as impurities, sodium oxide, potassium oxide, silicon oxide, calcium oxide, ferric oxide and titanium oxide in a total amount in the range from 100 to 10000 ppm, in which a total amount of the sodium oxide and potassium oxide based on the total amount of the impurities is not more than 4 wt. %. In the manufacture of the sintered body, its starting powder is admixed with at least an acid compound to produce metal salts by a reaction of the acid compound with metals contained in the starting powder and the resulting metal salts are removed.

Abstract: A novel gelation-resistant alumina and process for producing such a product and aqueous slurries composed thereof are disclosed, including grinding aluminum oxide of .alpha.-Al.sub.2 O.sub.3 in the presence of about 0.5 to 3.0 wt. % water. The grinding preferably is performed in a sealed ball mill. Dual phase alumina particles have an aluminum oxide inner core of .alpha.-Al.sub.2 O.sub.3 and an aluminum oxide hydroxide outer phase of .gamma.-AlOOH on the .alpha.-Al.sub.2 O.sub.3, including to a nominal depth, e.g., by way of example, of about 5 to 100 nanometers on the inner core of .alpha.-Al.sub.2 O.sub.3, and having up to 40% higher surface area than the initial aluminum oxide of .alpha.-Al.sub.2 O.sub.3. The novel gelation-resistant alumina can be dispersed in an aqueous slurry having a solids content of 65 wt. % and higher, and the resulting slurry has significantly extended shelf life.

Abstract: In the present invention, alumina is produced by a process comprising leading a starting aqueous slurry containing a seed alumina hydrate to a circulating system, the aqueous slurry being circulated and returned to the starting aqueous slurry, wherein an aqueous solution of an aluminum salt and an aqueous solution of a neutralizer are added to the aqueous slurry being circulated and mixed together at a pH value of 6 to 11 to thereby cause the aqueous slurry to contain formed alumina hydrate prior to the return to the starting aqueous slurry.

Abstract: A method for producing phase-pure, monodispersed, single crystal alpha-alumina particles of controlled size and shape comprises the steps of providing an aluminum hydrous oxide precursor and a glycol solution, dispersing said precursor in said glycol solution to create a suspension, heating and stirring said suspension in a closed pressure vessel to produce alpha-alumina particles, cooling said suspension, and removing said alpha-alumina particles from said solution. Additionally nucleation seeds may be added to the solution. Control of size is a function of seeding concentration, and control of morphology is a function of stirring rate.

Abstract: A novel gelation-resistant alumina and process for producing such a product and aqueous slurries composed thereof are disclosed, including grinding aluminum oxide of .alpha.-Al.sub.2 O.sub.3 in the presence of about 0.5 to 3.0 wt. % water. The grinding preferably is performed in a sealed ball mill. Dual phase alumina particles have an aluminum oxide inner core of .alpha.-Al.sub.2 O.sub.3 and an aluminum oxide hydroxide outer phase of .gamma.-AlOOH on the .alpha.-Al.sub.2 O.sub.3, including to a nominal depth, e.g., by way of example, of about 5 to 100 nanometers on the inner core of .alpha.-Al.sub.2 O.sub.3, and having up to 40% higher surface area than the initial aluminum oxide of .alpha.-Al.sub.2 O.sub.3. The novel gelation-resistant alumina can be dispersed in an aqueous slurry having a solids content of 65 wt. % and higher, and the resulting slurry has significantly extended shelf life.

Abstract: Alumina agglomerates having controlled porosity and excellent mechanical properties, well suited as catalyst supports and adsorbents, are produced by (a) agglomerating an alumina powder prepared by rapidly dehydrating an aluminum hydroxide, (b) aging the agglomerates thus formed in an atmosphere of controlled humidity, (c) impregnating such aged agglomerates with a solution of at least one acid, (d) hydrothermally treating the thus impregnated agglomerates in a confined enclosure, and then (e) drying and calcining the agglomerates thus treated.

Abstract: A stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 up to 15% by weight and 0.1 to 0.5 gram equivalent of an anion of acid to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a controlled thickness in a range of 20 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons is produced by a process comprising feeding an aqueous solution of an acid into an aqueous slurry containing 1 to 7% by weight of metallic aluminum, 10 to 200 ppm by weight as SiO.sub.2 of a water-soluble silicate and 0 to 20 ppm by weight of a water-soluble sulfate as SO.sub.4 to the water in the slurry while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.

Abstract: A process for making high porosity boehmite alumina comprising forming an aqueous dispersion of a boehmite alumina which has been obtained by hydrothermally treating an aqueous mixture of a precursor boehmite alumina at a pH of from about 5 to about 9 for a period of time sufficient to convert the greater portion of the precursor boehmite alumina to a colloidal sol, treating the dispersion of the hydrothermally treated alumina to form a viscous gel and subjecting the gel to sufficient shearing force for a sufficient period of time to increase the pore volume by at least 30% and the median pore radius by at least 20%.

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: Provided is a process for preparing alumina agglomerates which comprises:(i) treating agglomerates of active alumina with an aqueous medium comprising at least one acid making it possible to dissolve at least part of the alumina and at least one compound providing an anion capable of combining with aluminum ions in solution,(ii) subjecting the agglomerates to a hydrothermal treatment at a temperature in the range of from about 80.degree. C. to about 250.degree. C., and then(iii) thermally activating the agglomerates at a temperature in the range of about 500.degree. C. to about 1100.degree. C.The resulting alumina agglomerates possess exceptional mechanical strength, heat resistance and hydrothermal resistance and are useful as catalysts or catalyst supports.