Synthesis and characterization of Fe2O3 containing aluminas by thermal decomposition of modified ammonium dawsonite

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, Mossbauer, 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 Angstrom) also contain very small Fe2O3 particles (<10 nm) at higher Fe contents.