Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions
✍ Scribed by Gregorio Guadalupe Carbajal Arizaga; Fernando Wypych; Felipe Castillón Barraza; Oscar Edel Contreras Lopez
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 548 KB
- Volume
- 183
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 Å, typical for nitratecontaining LDHs, and another phase with a basal distance of 13.9 Å. Thermal treatment at 150 1C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 Å. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH 4 (NH 3 ) n ] + species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 Å basal distance) at pH ¼ 7, as well as a pure crystalline phase with 13.9 Å basal distance at pH ¼ 10 due to ammonia intercalation that can be removed by heating at 150 1C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions.