Mixed Mg(Al)O oxides synthesized by the combustion method and their recrystallization to hydrotalcites

Hydrotalcite-like compounds were successfully synthesized by using the combustion method from aluminum and magnesium nitrates and sodium carbonate. Sugar (saccharose) was used as fuel. The fuel amount, carbonate amount, and synthesis temperature were systematically varied. Furthermore, the obtained hydrotalcites were calcined until lattice destruction and recrystallized in presence of a carbonate aqueous solution. This cycle (memory effect) was sequentially reproduced three times. The resulting structural modifications were evaluated by solid-state nuclear magnetic resonance and X-ray diffraction, and compared with those observed, under similar conditions, in hydrotalcites prepared by co-precipitation and sol-gel methods. (C) 2007 Elsevier Inc. All rights reserved.