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Journal of Materials Science

, Volume 29, Issue 13, pp 3441–3450 | Cite as

Phase composition and mechanism of formation of Ba-β-alumina-type systems for catalytic combustion prepared by precipitation

  • G. Groppi
  • C. Cristiani
  • P. Forzatti
  • M. Bellotto
Article

Abstract

A novel preparation method is proposed for Ba-β-Al203-type systems to be used in high-temperature catalytic combustion, consisting of precipitation in aqueous medium. Differential thermal analysis-thermogravimetry, X-ray diffraction, Fourier transform-infrared, TEM and surface area data are presented for Ba-Al-O samples with Al/Ba atomic ratios in the range 14-9 calcined at different temperatures up to 1670 K. The final materials consist of a barium-poor Ba-β1Al2O3 phase together with 1% α-Al2O3 in the case of Al/Ba = 14 and of a barium-rich Ba-β11-Al2O3 phase together with 2% BaAl2O4 in the case of Al/Ba = 9. A mono-phasic sample with a Ba-β-Al2O3 structure is obtained in the case of Al/Ba = 12; this phase is constituted by the simultaneous presence of both β1 and β11 structure types. Two routes operate above 1370 K in the formation of the Ba-β-Al2O3 phases involving solid-state reactions between γ-Al2O3 and BaAl2O4, and γ-Al2O3 and dispersed barium compounds. Based on the analogies between the structures of γ-Al2O3 and of the Ba-β-Al2O3 phases it is suggested that the formation of the latter occurs via diffusion of barium ions within oxygen close-packed planes of the γ-Al2O3-type spinel structure.

Keywords

Barium Atomic Ratio Spinel Structure Simultaneous Presence Area Data 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • G. Groppi
    • 1
  • C. Cristiani
    • 1
  • P. Forzatti
    • 1
  • M. Bellotto
    • 2
  1. 1.Dipartimento di Chimica Industriale e Ingegneria Chimica “G. Natta” del PolitecnicoMilanoItaly
  2. 2.CISESegrate MilanoItaly

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