US Patent 7981836 Hydrothermally stable alumina

The hydrothermal stability of transition aluminas used as adsorbents and catalyst carriers is improved through their treatment with a soluble silicon inorganic compound such as sodium silicate wherein the silicon compound is mixed with the alumina powder at the production stage of forming particulates by liquid addition. The silicon containing particulates are activated by heating at a temperature lower than 500° C. and treated, before or after the thermal activation, by a colloidal silica solution to produce a hydrothermally stable, low dust alumina. The total silica content of the final product is typically less than 5 mass-%.