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

Abstract

Aluminas with Fe 2 O 3 particles finely divided in the Al 2 O 3 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, Mo ¨ssbauer, TEM and adsorption measurements shows that all the Fe 3z 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 A ˚) also contain very small Fe 2 O 3 particles (v10 nm) at higher Fe contents.

Partial oxidation of polyvalent oxygen substituted compounds on nano-scale gold catalysts

“…Different alumina materials were used as support: Al 2 O 3 (P)-␥-Al 2 O 3 Puralox HP14/150 (Sasol/Condea, S BET = 151 m 2 /g) and Al 2 O 3 (D)-high specific surface area Al 2 O 3 prepared from ammonium dawsonite ((NH 4 Al(OH) 2 CO 3 ), S BET = 516 m 2 /g) [4]. Au/Al 2 O 3 catalysts were prepared by deposition/precipitation using HAuCl 4 and NaOH and urea, respectively, as precipitation agents.…”

“…Au/Al 2 O 3 catalysts were prepared by deposition/precipitation using HAuCl 4 and NaOH and urea, respectively, as precipitation agents. In both the cases Mg citrate was used as additive to stabilise the Au dispersity [5].…”

Stability and inter-conversion of synthetic dawsonites in aqueous media

“…They are also attractive precursors for ceramic and catalytic-grade alumina-based materials with remarkable properties (Pitsch et al, 2001;Ali et al, 2005;Santiago et al, 2006;Santiago and Pérez-Ramírez, 2007; 0016-7037/$ -see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.gca.2010.09.013 Stoica et al, 2009a,b,c;Masuda et al, 2009).…”

In-line dispersion–precipitation method for the synthesis of metal-substituted dawsonites. Genesis of oxide materials with superior properties

“…Ali et al 5 have recently extrapolated the dawsonite route to prepare bulk Cr 2 O 3 and Fe 2 O 3 by isomorphous substitution of Al by Cr or Fe in the precursor structure, but low-surface area oxides (,32 m 2 g 21 ) were obtained. Pitsch et al 6 prepared bimetallic Fe-Al dawsonites by discontinuous precipitation using NH 4 Fe(SO 4 ) 2 as the iron source. Upon calcination at 873 K, Fe 2 O 3 /Al 2 O 3 catalysts (1-10 wt% Fe) with relatively high surface areas (up to 400 m 2 g 21 ) were attained.…”