Managing Properties of Alumina Based Granules Prepared by Disk (Dished) Molding

Abstract

Alumina-based spherical granules were prepared by disk granulation. Products of gibbsite thermoactivation in various reactors were used as the initial materials. In the course of molding, combustible additives (starch, carbon, wood meal) were added to the thermoactivated gibbsite powder, and NaOH (10 %), C₂H₅OH (15 %), Н₃ВО₃ (6 %) to the wetting solution (H₂O). With the product of centrifugal thermoactivation of hydrargillite, the prepared granules were stronger at the larger average size of pores; addition of NaOH, C₂H₅OH and H₃BO₃ led to an increase in the specific surface area and micropore proportion but had different effects on the mechanical strength of the granules. Introduction of combustible additives (wood meal, activated carbon) affected only slightly the specific surface area, favored an increase in the total pore volume and mesopore volume, resulted in a decrease in bulk density and mechanical strength of the granules. Conditions were determined for preparation of a highly effective strong dessicant with large specific surface area (up to 340 m²/g) and average pore diameter up to 3.4 nm. Conditions were determined for preparation of strong ultramacroporous granules that are highly active to the Klaus process.