Process for preparation of ferrierite type zeolites

Claim 1

A process for preparing ferrierite type zeolites, which comprises the steps of: (1) supplying an aqueous alkali metal silicate solution simultaneaously and continuously with an aqueous aluminum-containing solution at substantially constant rates to a reactor while a reaction slurry having the reaction product suspended therein is continuously withdrawn therefrom so that the residence time of the reaction slurry in the reactor is at least three minutes and the pH of the reaction slurry is maintained at a value of 5 to 9, thereby to obtain a homogeneous phase compound of a granular amorphous aluminosilicate having a particle size of 1 to 500 μm and containing aluminum in an amount of 3 to 14% by weight as calculated as anhydrous Al 2 O 3 and an alkali metal in an amount of 1 to 17% by weight as calculated as anhydrous A 2 O wherein A is a metal selected from the group consisting of sodium and potassium; and thereafter (2) crystallizing the homogeneous phase compound of the granular amorphous aluminosilicate at a temperature of 100° to 300° C. in the form of a slurry in water or in an aqueous solution containing up to 13% by weight of sodium hydroxide or a mixture of sodium hydroxide and potassium hydroxide; the molar ratio of potassium ions (K + ) to the total alkali metal cations (K + +Na + ) in said slurry being in the range of from 0.2 to 0.7; the molar ratio of the total alkali metal hydroxide component as AOH (where A is alkali metal) in the slurry to the silicon component as SiO 2 in the homogeneous phase compound is in the range of from 0.1 to 0.35; and the weight ratio of the total solids to the slurry for crystallization is in the range of 0.04 to 0.4.