The effect of preparation procedure for precursor on the morphology, surface area and porosity of alumina powders

Abstract

In order to investigate the effect of preparation procedure for precursors on some physico-chemical properties of powders, three alumina precursors were prepared by different ways. The first precursor (P1) was precipitated by adding ammonia to the boiling aluminium sulphate solution buffered by NH3/NH4Cl (pH = 9.25). The second precursor (P2) was precipitated by the reaction between aluminium sulphate and excess urea in boiling aqueous solution (pH = 3.42). The third precursor (P3) was precipitated by the similar reaction in boiling aqueous solution buffered by C2H4(COOH)(2)/C2H4(COONH4)(2) (pH = 4.16). Three different alumina powders (P1, P2 and P3) were obtained by the calcination of the precursors at 1000 degrees C for 2 h. The powders were examined by scanning electron microscopy and nitrogen adsorption-desorption techniques. The BET specific surface areas (A) and specific micro-mesopore volumes (V) for the powders (P1, P2 and P3) were obtained as 116 m(2) g(-1) and 0.34 cm(3) g(-1), 66 m(2) g(-1) and 0.15 cm(3) g(-1) and 148 m(2) g(-1) and 0.59 cm(3) g(-1), respectively. The surface areas of the powders determined by other methods, are compared with the BET values.