Abstract

Aluminas with Fe₂O₃ particles finely divided in the Al₂O₃ matrix were prepared via a crystalline precursor derived from ammonium dawsonite and its calcination. The precursors with Fe content between 1 and 10 wt% were synthesized by reaction of ammonium hydrogen carbonate with mixtures containing aluminium ammonium sulfate and ferric ammonium sulfate. The characterization of the as-synthesized and calcined products by chemical analysis, XRD, EPR, Mössbauer, TEM and adsorption measurements shows that all the Fe³⁺ ions are incorporated into the structure of dawsonite when the Fe content is low and that the calcined materials with micropores and mesopores (maximum 30–40 Å) also contain very small Fe₂O₃ particles (<10 nm) at higher Fe contents.