Formation of Alkali‐Aluminosilicate Layers on Thermochemically Dealuminated Y Zeolites by Alkaline Leaching

Zeolite Y was steamed at 873 K for 7 h. This thermochemical treatment increases the Si/Al ratio of the zeolite framework from 2.4 to 3.8 under the formation of non‐framework aluminium species. Successive leaching in 0.25 M KOH at 353 K for 24 h decreases the Si/Al ratio of the zeolite to 2.6 due to the formation of a X‐ray amorphous potassium aluminosilicate surface layer.