PRECIPITATED ALUMINA AND METHOD OF PREPARATION

摘要

A process for producing alumina, the process having a seeding phase and a precipitation phase. During the seeding phase a seed mixture is produced by adding an aluminium salt to an aqueous solution and then adding an alkaline metal aluminate to the mixture while maintaining the seed mixture at generally neutral pH. The precipitation phase produces precipitated alumina by simultaneously adding aluminium salt and alkaline metal aluminate to the seed mixture while maintaining a pH from 6.9 to 7.8. The recovered precipitated alumina has at least one, preferably all the following characteristics: i) a crystallite size of 33-42 Ang.: in the (120) diagonal plane (using XRD).; ii) a crystallite d-spacing (020) of between 6.30 - 6.59 Ang.; iii) a high porosity with an average pore diameter of 115-166 Ang.; iv) a relatively low bulk density of 250-350 kg/m3; v) a surface area after calcination for 24 hours at 1100º C of 60-80 m2/g; and vi) a pore volume after calcination for one hour at 1000ºC 0.8-1.1 m3/g.