B. Herreros et J. Klinowski, INFLUENCE OF THE SOURCE OF SILICON AND ALUMINUM IN THE HYDROTHERMAL SYNTHESIS OF SODALITE, Journal of the Chemical Society. Faraday transactions, 91(7), 1995, pp. 1147-1154
Citations number
22
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The synthesis of sodalite from aluminium hydroxide, aluminium isopropo
xide and pseudo-boehmite (Catapal alumina) as the source of Al, and fu
med silica and sodium silicoglycolate (Na-Si(v)) as the source of Si h
as been monitored by solid-state NMR, X-ray diffraction (XRD) and IR s
pectroscopy. The use of Na-Si(v) does not affect the crystallization t
ime, but considerably shortens the preparation of the synthesis gel. A
luminium is not significantly incorporated into the sodalite structure
when Al(OH)3 is used. Pseudo-boehmite gives multi-phasic products in
which purely siliceous sodalite is always accompanied by (Si,Al)-sodal
ites. Some of the Al occupies non-framework positions, and parent gels
with Si:Al = 5.0, 2.0 and 1.0 gave solids with Al(iv):Al(vi) = 0.73,
1.3 and 3.0, respectively. Only aluminum isopropoxide leads to phase-p
ure products in which all the Al is four-coordinate and Si:Al = 3.49 a
nd 3.13 with fumed silica and Na-Si(v), respectively. The formula N(Al
) = 51.855 - 0.0465nu(as)(Si-O-T) allows the Si:Al ratio to be calcula
ted directly from the FTIR spectrum. With the exception of the materia
l with Si:Al = 1.0 and a(o) = 8.94 +/- 0.1 angstrom, the unit cell par
ameter of sodalites is 8.83 +/- 0.1 angstrom irrespective of the Al co
ntent.