초록 ▼

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, oxalat

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°C. to decompose the aluminum compound to alumina or an alumina hydrate. The body is optionally further heated subsequent to the hydrothermal treatment.

대표청구항 ▼

A process for the preparation of a shaped body having at least one dimension less than 100 microns and comprising alumina in either noncrystalline form or in predominantly eta form or both and free of alpha-alumina which includes the steps of: (a) forming into the desired shape of body a composition

A process for the preparation of a shaped body having at least one dimension less than 100 microns and comprising alumina in either noncrystalline form or in predominantly eta form or both and free of alpha-alumina which includes the steps of: (a) forming into the desired shape of body a composition having a viscosity in the range 0.1 to 5000 poise and comprising a water-soluble aluminum compound decomposable to alumina and selected from the group consisting of the chlorides, sulphates, acetates, formates, propionates, oxalates, phosphates and nitrates of aluminum or mixtures thereof, a water soluble organic polymer having a molecular weight in the range 103 to 107 and present in an amount by weight less than the aluminum compound, and water; (b) removing at least part of the water from the body so formed; (c) subjecting the body to hydrothermal treatment at a temperature of from 200°-800°C. for 2 minutes to 5 hours to decompose at least partially the aluminum compound to alumina or an alumina hydrate; and (d) calcining the hydrothermally treated body at a temperature of from 600°to 1000°C. for a period of one minute to one hour so as to obtain the alumina in either noncrystalline form or in predominantly eta crystalline form or both and free of alpha-alumina.