Patent ID: 6653396
Filing Date: 2003-11-25
Classification: C01B,C08G

Abstract:
A process for the preparation of zeolites having a zeolite A structure with an Si/Al atomic ratio of between 0.95 and 1.1, all the cationic sites of which are occupied by sodium, calcium and/or magnesium, potassium and hydronium cations, comprising, given in equivalents:from 10 to 69% of sodium ions, from 28 to 55% of potassium ions, from 2 to 45% of calcium and/or magnesium ions, and from 1 to 20% of hydronium ions, the sum of the sodium, potassium, calcium and/or magnesium, and hydronium cations (given in equivalents) being equal to 100%, said process comprising the following stages: 1/ bringing the following aqueous solutions or suspensions into contact: a-i an aqueous suspension of zeolite 3A(a-1), 4A(a-2) or 5A(a-3), b-j an aqueous saline solution of calcium salt(s) (b-1), or of potassium salt(s) (b-3), or solutions of calcium and potassium salt(s) (b-2), c an acid solution according to one or other of the following methods: either a-i, b-j and c simultaneously or a-i and b-j, then c, or a-i and c, then b-j, or b-j and c, then a-i, with, in all cases, i and j being identical, 2/ then filtering off and washing the solid obtained, 3/ then drying and activating by heat treatment, the solid resulting from 2/.