Process for the manufacture of zeolites 4A having a high crystallinity and a fine granulometry and being particularly suitable for the formulation of detergent compositions

摘要

The synthesis of zeolites 4A having a high crystallinity and a fine granulometry is disclosed, by the addition in a first stage of a sodium silicate solution to a sodium aluminate solution (containing an excess of NaOH and heated to a temperature of from 50 DEG to 100 DEG C.), and by the crystallization in a second stage at a temperature of from 70 DEG to 105 DEG C., characterized in that the temperature of the sodium silicate solution is lower by at least twenty Centigrade degrees than that of the sodium aluminate solution, the molar ratios SiO2:H2O and SiO2:Na2O in the sodium silicate solution being respectively from 0.030 to 0.150 and from 1.95 to 2.30, and the weight ratio between the reaction mother liquor and the zeolite thus formed being from 6.5 to 20.