Zeolite L synthesis

A process for the preparation of zeoliteL, in which a reaction mixture comprising water, a source of potassium, a course of silicon, a source of aluminium is heated to a temperature of at least 75.degree. C. to form the desired zeolite L, characterised in that the reaction mixture contains copper and that the reaction mixture is such that in the absence of copper the formed product would comprise substantial amounts by zeolite W, the amount of copper being such that its presence results in reduced contamination by zeolite W.

A method of suppressing zeolite W formation in the preparation of zeolite L from a crystallization gel in which the crystallization conditions would otherwise allow zeolite W formation, which method comprises introducing into the gel a zeolite W-suppressing amount of a source of copper

A method of reducing the crystallite size of zeolite L prepared from a synthesis gel for forming zeolite L, in which there is introduce into the synthesis gel from 0.1 ppm to 0.1 wt. % of copper based on the weight of the gel.

A stirred synthesis for zeolite L, in which a zeolite W-suppressing amount of copper is introduced into a reaction mixture capable of forming zeolite L in a static synthesis and the reaction mixture containing copper is heated to a temperature of at least 75.degree. C. with stirring to form zeolite L.

Zeolite L containing copper in non-exchangeable sites in the zeolite L structure.