A process for producing a porous alpha-alumina catalyst support, comprising i) preparing a precursor material comprising, based on inorganic solids content, at least 50 wt.-% of a transition alumina having a loose bulk density of at most 600 g/L, a pore volume of at least 0.6 mL/g and a median pore diameter of at least 15 nm; and at most 30 wt.-% of an alumina hydrate; ii) forming the precursor material into shaped bodies; and iii) calcining the shaped bodies to obtain the porous alpha-alumina catalyst support. The catalyst support has a high overall pore volume, thus allowing for impregnation with a high amount of silver, while keeping its surface area sufficiently large so as to provide optimal dispersion of catalytically active species, in particular metal species. The invention further relates to a shaped catalyst body for producing ethylene oxide by gas-phase oxidation of ethylene, comprising at least 15 wt.-% of silver, relative to the total weight of the catalyst, deposited on a porous alpha-alumina catalyst support obtained in the process described above. The invention also relates to a process for preparing a shaped catalyst body as described above comprising impregnating a porous alpha-alumina catalyst support obtained in the process described above with a silver impregnation solution, preferably under reduced pressure; and optionally subjecting the impregnated porous alumina support to drying; and b) subjecting the impregnated porous alpha-alumina support to a heat treatment; wherein steps a) and b) are optionally repeated. The invention further relates to a process for producing ethylene oxide by gas-phase oxidation of ethylene, comprising reacting ethylene and oxygen in the presence of a shaped catalyst body as described above.

A blended composition containing uncoated Al.sub.2O.sub.3 flakes having a thickness of ≥500 nm and a D.sub.50-value of 15-30 μm and a D.sub.90-value of 30-45 μm, and/or coated Al.sub.2O.sub.3 flakes having a thickness of ≥500 nm and a D.sub.50-value of 15-30 μm and a D.sub.90-value of 30-45 μm, which have been coated with at least one layer of a metal oxide, mixtures of at least two metal oxides, metal, metal sulphide, titanium suboxide, titanium oxynitride, FeO(OH), metal alloys and/or rare earth compounds, and their use in various formulations.

The present invention relates to: an antibacterial composite material with a bactericidal effect, having a shape in which aluminum hydroxide is coupled, in an island form, to the surface of a copper compound; and a preparation method therefor, and since the antibacterial composite material rapidly exhibits an immediate bactericidal effect against bacteria or viruses for a short time of five minutes or less and the bactericidal effect is maintained for a long time, the antibacterial composite material is usable in various fields requiring an antibacterial effect, and thus an effective antibacterial and antiviral function can be provided.

The present invention refers to a process for the preparation of a high surface area nanoparticulate alpha alumina.

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 α-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 α-alumina is preferably not greater than 10 m.sup.2/g. A particle diameter D50 equivalent to 50% cumulative percentage by volume of the α-alumina is also preferably not greater than 2 μm.

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.

An abrasive grain is disclosed and may include a body. The body may define a length (l), a height (h), and a width (w). In a particular aspect, the length is greater than or equal to the height and the height is greater than or equal to the width. Further, in a particular aspect, the body may include a primary aspect ratio defined by the ratio of length:height of at least about 2:1. The body may also include an upright orientation probability of at least about 50%.

A process of forming a sintered article includes heating a green portion of a tape of polycrystalline ceramic and/or minerals in organic binder at a binder removal zone to a temperature sufficient to pyrolyze the binder; horizontally conveying the portion of tape with organic binder removed from the binder removal zone to a sintering zone; and sintering polycrystalline ceramic and/or minerals of the portion of tape at the sintering zone, wherein the tape simultaneously extends through the removal and sintering zones.

The present disclosure is directed to an alpha alumina powder having a specific surface area, a specific crystallite size, and a specific particle size distribution for use in abrasive polishes, and method of making such powder. The method of making the alpha alumina powder can include calcining an aluminum oxide precursor powder at a temperature of 800-1500° C. and milling the calcined powder to the specific particle size distribution. The alpha alumina powder disclosed herein can quickly enable high removal rate with undiminished aesthetic quality when used in abrasive polishes.

A process of forming a sintered article includes heating a green portion of a tape of polycrystalline ceramic and/or minerals in organic binder at a binder removal zone to a temperature sufficient to pyrolyze the binder; horizontally conveying the portion of tape with organic binder removed from the binder removal zone to a sintering zone; and sintering polycrystalline ceramic and/or minerals of the portion of tape at the sintering zone, wherein the tape simultaneously extends through the removal and sintering zones.