Synthesis and structural characterization of mixed aluminum-gallium-offretites

✍ Scribed by Axel Wölker; Christopher Hudalla; Hellmut Eckert; A. Auroux; Mario L. Occelli

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 913 KB
• Volume: 9
• Category: Article
• ISSN: 0926-2040
• DOI: 10.1016/s0926-2040(97)00021-0

✦ Synopsis

A new synthesis procedure is reported for the preparation of mixed Al,Ga-offretites over the entire solid solution range 0 5 Ga/(Ga + Al) I 1. The resulting materials are characterized by X-ray powder diffraction, adsorption microcalorimetry and multinuclear solid state NMR. The 29Si MAS-NMR data are consistent with statistical occupancy of the T, and T2 sites by aluminum and gallium, and also show no positive evidence for preferential siting effects between both framework metals. Isotropic chemical shifts and nuclear electric quadrupolar coupling constants for "Al and "Ga have been obtained from a field-dependent analysis of the center of gravity in the MAS-NMR spectra. H-Al,Ga-offretites produced by ammonium exchange and subsequent calcination reveal evidence of partial demetallation of the framework with formation of extra-lattice metal species. 0 1997 Elsevier Science B.V.