Abstract: The precursor of alumina, ammonium aluminum carbonate hydroxide (AACH) with the chemical composition corresponding to NH₄[AlO(OH)]₂HCO₃^.2H₂O, was prepared from aluminium sulfate solution and ammonium bicarbonate solution through chemical coprecipitation method. The effect of pH and temperature on the preparation of AACH was studied on the basis of the precipitating mechanism. The prepared alumina from calcination of AACH showed high pore volume and large pore size,was suitable to be used as the support material of residue hydrotreating catalyst, and could also be compounded with other pseudo-boehmites to form supports with different pore structures to meet different requirements. The results of activity evaluation and commercial application showed that the residue hydrodemetallization catalyst based on the AACH had good performance of demetallization and reduction of carbon residue.

Key words: Ammonium aluminum carbonate hydroxy hydrate, pore volume, pore size, alumina