Characterisation of fine alumina powders of maximum porosity prepared by emulsion evaporation

Abstract

Water in oil emulsions were prepared by A1(N03)3 solutions having various concentrations between 0.25 - 2.00 M. The emulsion droplets were investigated by optical microscopy. Infinitely stable emulsions were evaporated by dropping them into hot mineral oil. The precipitated dark brown precursors were calcined at 1000°C and fine alumina powders were obtained. Adsorption and desorption of nitrogen on the powders was realized at 77K. The specific surface areas (A) and the specific micropore-mesopore volumes (V) were determined respectively from the data of adsorption and desorption. The variation of the A and V values as a function of the concentration of A1(N03)3 solutions was determined. The powder which had the maximum A and V values, was characterised by taking its photograph by an electron microscope and also by determining its particle size distribution and mesopore size distribution.