PREFER - A NEW LAYERED (ALUMINO) SILICATE PRECURSOR OF FER-TYPE ZEOLITE

A new layered microporous (alumino) silicate showing (100) ferrierite layers and called PREFER was synthesised from fluoride-containing aque ous media in the presence of a novel bulky template, the 4-amino-2,2,6 ,6-tetramethyl-piperidine. Calcination at about 500 degrees C of this 'as-made' product leads to FER-type zeolite by a transformation occurr ing through the intermediate formation of poorly organised phases. The whole set of results obtained by several techniques such as variable- temperature XRD, chemical and thermal analyses and Si-29 MAS NMR spect roscopy are consistent with a 2D-->3D transformation process. Indeed, during the calcination, the (100) ferrierite layers progressively link together through condensation reactions between the Q(3)-type silicon atoms initially present.