Abstract: MFI zeolites based on silicon oxide and, optionally, the oxides of titanium, germanium, zirconium and/or tin, are produced by (1) heating an aqueous, homogeneous reaction mixture which comprises (a) an M.sub.2/n SiF.sub.6 complex (I), wherein M is a cation of valency n, optionally, at least one M.sub.2/n T'F.sub.6 complex (II), wherein T' is titanium, zirconium, germanium and/or tin, (b) a reagent providing OH. ions by hydrothermal decomposition and a structuring agent (c), e.g., a tertiary amine or a quaternary ammonium compound, whereby a zeolite precipitate is formed therein, and (2) separating and calcining such precipitate to eliminate structuring agent from the pores and channels of the resulting zeolite.

Abstract: An aluminosilicate gel containing an ST structuring agent whose composition is suitable for crystallization into a zeolite of the faujasite structural family is prepared. The gel then undergoes crystallization in order to form a zeolite precursor which consists of the zeolite containing the ST structuring agent in its cavities and channels, the zeolite being produced through the calcination of the precursor. The ST structuring agent consists of at least one compound from the alkylene polyoxides of formula (1) ##STR1## in which R and R', identical or different, each represents H or an alkyl radical in C.sub.1 to C.sub.4, X designates H or OH, m is equal to 2 or 3 and can differ from one pattern to another, and n is a number from 1 to 12. The zeolites thus obtained have a Si:Al ratio which is greater than 1 and which can go beyond 3, and show a cubic symmetry. The zeolites can be used, directly or after cation exchange, as adsorbants or as catalyst constituents.