| 摘要 |
1. A process for producing a zeolite of type A with a high water absorption capacity, with an SiO2 / AI2 O3 molar ratio higher than 1.85 and advantageously at least equal to 2, characterized in that : (a) a mixture of solutions of sodium aluminate and silicate is made from a solution of aluminate which is advantageously cooled at from -10 to +10 C, and a solution of silicate, at a temperature such that the temperature of the resulting medium is substantially lower than the ambient temperature, with sufficient agitation being maintained to permit the formation of a homogenous solution having the appearance of a gel and with the molar ratio in the reaction medium being maintained at a value which is at least equal to 1.85 ; (b) the temperature of the reaction medium is raised to a value in the range of from 60 to 100 C ; (c) the medium is maintained at that temperature for a sufficient period of time of from 0.2 to 5 h, so as to cause crystallisation and redispersion of the silicoaluminate in the form of suspension of crystals in the liquid phase, and (d) the resulting crystals are separated and dried. |
