An object of the present invention is to provide an alumina used for a slurry for reducing unevenness in a surface of a porous membrane. The present invention is an ?-alumina wherein a crystallite size obtained by a Rietveld analysis is not greater than 95 nm, and a lattice strain obtained by the Rietveld analysis is not greater than 0.0020. A BET specific surface area by a nitrogen adsorption method of the ?-alumina is preferably not greater than 10 m.sup.2/g. A particle diameter D50 equivalent to 50% cumulative percentage by volume of the ?-alumina is also preferably not greater than 2 ?m.

An object of the present invention is to provide an alumina used for a slurry for reducing unevenness in a surface of a porous membrane. The present invention is an ?-alumina wherein a crystallite size obtained by a Rietveld analysis is not greater than 95 nm, and a lattice strain obtained by the Rietveld analysis is not greater than 0.0020. A BET specific surface area by a nitrogen adsorption method of the ?-alumina is preferably not greater than 10 m.sup.2/g. A particle diameter D50 equivalent to 50% cumulative percentage by volume of the ?-alumina is also preferably not greater than 2 ?m.

96 parts by mass of a -alumina powder, 4 parts by mass of a an AlF.sub.3 powder, and 0.17 parts by mass of an -alumina powder as a seed crystal were mixed by a pot mill. The purities of each raw material were evaluated, and it was found that the mass ratio of each impurity element other than Al, O, F, H, C, and S was 10 ppm or less. In a high-purity alumina-made sagger having a purity of 99.9 percent by mass, 300 g of the obtained mixed powder was received, and after a high-purity alumina-made lid having a purity of 99.9 percent by mass was placed on the sagger, a heat treatment was perforated at 900 C. for 3 hours in an electric furnace in an air flow atmosphere, so that an alumina powder was obtained. The value of AlF.sub.3 mass/container volume was 0.016 g/cm.sup.3.

A positive electrode includes a lithium-based active material, a binder, a conductive filler, and discrete aluminum oxide nanomaterials. The aluminum oxide nanomaterials are mixed, as an additive, throughout the positive electrode with the lithium-based active material, the binder, and the conductive filler. The positive electrode with the discrete aluminum oxide nanomaterials may be incorporated into a lithium ion battery. The aluminum oxide nanomaterials may be formed by the following method. A solution is formed by mixing an aluminum oxide precursor and an acid. A carbon material is added to the solution, thereby forming an aqueous mixture having the carbon material therein. Hydrothermal synthesis is performed using the aqueous mixture, and precursor nanostructures are grown on the carbon material. The precursor nanostructures on the carbon material are annealed so that the carbon material is removed and aluminum oxide nanomaterials are formed.

A supported catalyst having a calcined, predominantly aluminum, oxide support and an active phase of 5 to 65% by weight nickel with respect to the total mass of the catalyst, said active phase having no group VIB metal, the nickel particles having a diameter less than or equal to 20 nm, said catalyst having a mesopore median diameter greater than or equal to 14 nm, a mesopore volume measured by mercury porosimetry greater than or equal to 0.45 mL/g, a total pore volume measured by mercury porosimetry greater than or equal to 0.45 mL/g, a macropore volume less than 5% of the total pore volume, said catalyst being in the form of grains having an average diameter comprised between 0.5 and 10 mm. The invention also relates to the process for the preparation of said catalyst and the use thereof in a hydrogenation process.

A process for the preparation of an amorphous mesoporous and macroporous alumina: at least once dissolving an acidic precursor of aluminium, adjusting pH by adding at least one basic precursor to the suspension obtained in a), co-precipitation of the suspension obtained from b) by adding at least one basic precursor and at least one acidic precursor to the suspension, filtration, drying, shaping and heat treatment. An amorphous mesoporous and macroporous alumina with bimodal pore structure: a specific surface area S.sub.BET more than 100 m.sup.2/g; a median mesopore diameter, by volume determined by mercury intrusion porosimetry, 18 nm or more; a median macropore diameter, by volume determined by mercury intrusion porosimetry, 100 to 1200 nm, limits included; a mesopore volume, as measured by mercury intrusion porosimetry, 0.7 mL/g or more; and a total pore volume, as measured by mercury porosimetry, 0.8 mL/g or more.

A process for the preparation of an alumina in the form of beads with a sulphur content in the range 0.001% to 1% by weight and a sodium content in the range 0.001% to 1% by weight with respect to the total mass of said beads is described, said beads being prepared by shaping an alumina gel having a high dispersibility by drop coagulation. The alumina gel is itself prepared using a specific precipitation preparation process in order to obtain at least 40% by weight of alumina with respect to the total quantity of alumina formed at the end of the gel preparation process right from the first precipitation step, the quantity of alumina formed at the end of the first precipitation step possibly even reaching 100%. The invention also concerns the use of alumina beads as a catalyst support in a catalytic reforming process.

The present invention relates to an alpha alumina having a high purity, a high density and a low surface area and particularly, to a method to produce such an alpha alumina as well as to the use of the alpha alumina in sapphire production or the production of composite and ceramic bodies.

The present invention relates to an alpha alumina having a high purity, a high density and a low surface area and particularly, to a method to produce such an alpha alumina as well as to the use of the alpha alumina in sapphire production or the production of composite and ceramic bodies.

A system, process and related sintered article are provided. The process includes supporting a piece of inorganic material with a pressurized gas and sintering the piece of inorganic material while supported by the pressurized gas by heating the piece of inorganic material to a temperature at or above a sintering temperature of the inorganic material such that the inorganic material is at least partially sintered forming the sintered article. The inorganic material is not in contact with a solid support during sintering. The sintered article, such as a ceramic article, is thin, has high surface quality, and/or has large surface areas.