Process for the preparation of crystalline silicates

Claim 1

Crystalline iron silicates having the following properties: (a) thermally stable up to a temperature above 600° C., (b) an X-ray powder diffraction pattern showing, inter alia, the reflections given in Table A of the specification, (c) in the formula that represents the composition of the silicate, expressed in moles of the oxides, and in which, in addition to oxides of hydrogen, alkali metal and silicon iron oxide is present, the SiO 2 /Fe 2 O 3 molar ratio (m) is more than 10, which process comprises said silicates being prepared according to a process which comprises maintaining at a temperature between about 90° to about 300° C. for a period of 4 hours or more, until the crystalline silicate is formed, an aqueous mixture containing the following compounds: one or more compounds of an alkali metal (M), one or more amines with the general formula R 1 R 2 R 3 N, in which R 1 represents an alkyl group and R 2 and R 3 represent an alkyl group or a hydrogen atom, one or more silicon compounds which yield, after drying at 120° C. and calcining at 500° C., a product with an SiO 2 content higher than 90%w and one or more iron compounds, in which mixture the compounds, with the exception of the amines, are present in the following molar ratios, expressed in moles of the oxides: M 2 O: SiO 2 =0.01-0.35, R 1 R 2 R 3 N: SiO 2 =0.04-1.0, SiO 2 : Fe 2 O 3 >10, and H 2 O: SiO 2 =5-65, then separating said crystalline silicate from the mother liquor, and calcining said separated silicate.