Process for preparation of high-silica faujasite type zeolite

Claim 1

A process for the preparation of a high-silica faujasite type zeolite having a silica/alumina ratio of at least 4.5, which process comprises the steps of: (a) simultaneously and continuously supplying an aqueous solution of an alkali metal silicate and an aqueous solution of an aluminum-containing compound into a reaction zone whereby the alkali metal silicate is continuously reacted with the aluminum-containing compound to prepare a homogeneous phase compound of a granular amorphous aluminosilicate containing, based on the anhydride, 10 to 16% by weight as Al 2 O 3 , of aluminum, about 74.52 to about 83.67% by weight, as SiO 2 , of silica and about 6.17 to about 9.63% by weight, calculated in terms of Na 2 O, of alkali metal, said granular homogeneous phase amorphous aluminosilicate prepared in the reaction zone in the form of an aqueous slurry having a pH value of 5 to 9; (b) subjecting the aqueous slurry of the granular homogeneous phase amorphous aluminosilicate to solid-liquid separation; (c) aging a part of the granular homogeneous phase amorphous aluminosilicate thus separated in an aqueous alkali metal hydroxide solution at a temperature of 10° to 95° C. for 0.5 to 12 hours; and then (d) crystallizing a mixture of the aged granular homogeneous phase amorphous aluminosilicate and the nonaged granular homogeneous phase amorphous aluminosilicate in an aqueous alkali metal hydroxide solution having a concentration of 4 to 10% by weight.