Prodn. of finely divided zeolite(s) of ZSM-5 type - by two=stage hydrothermal crystallisation

摘要

Prodn. of finely divided zeolites of ZSM-5 type, having an X-ray powder diffraction pattern with d-spacings of 11.1 +/- 0.2, 10.1 +/- 0.2, 3.85 +/- 0.07, 3.74 +/- 0.05 and 3.72 +/- 0.05 Angstroms, is effected by: (a) preparing a nucleating slurry of the semicrystalline zeolite with a BET surface area of 100-250 m2/g; (b) mixing the nucleating slurry with an aq. reaction mixt. contg. silica, alumina and alkali metal sources; (c) heating the mixt. under agitation to form a slurry of zeolite particles with a BET surface area of 100-200 m2/g; (d) mixing at least part of the slurry from (c) with an aq. reaction mixt. contg. silica, alumina and alkali metal sources; (e) heating the mixt. to form a product slurry of zeolite particles with a BET surface area of at least 250 m2/g; and (f) opt. isolating the zeolite particles from the product slurry.