Stability and thermal transformation studies of Zn2+- and Fe2+- loaded zeolite Y prepared from Egyptian kaolin

• Loading processes of Zn2+ and Fe2+ ions affect the stability of zeolite Y.
• Stability and loading mechanisms depend on TM type and the experimental conditions.
• ZnAl2O4 and silica phases were formed upon heating of Zn2+-zeolites.
• Nepheline, aluminosilicates and other oxides were formed upon heating Fe2+-zeolites.
• Ratios of the formed phases depend on the amount of TM in the unheated zeolites.

The stability and thermal transformation of Zn2+ and Fe2+- zeolites based kaolin were studied with respect to their loading experimental conditions. Zeolite Y prepared from Egyptian kaolin was used in our investigations. Zeolite shows different degrees of framework stability according to the type of cation and the loading experimental conditions. The obtained data indicate the predominance of adsorption and ion exchange mechanisms during Fe2+ and Zn2+ loading, respectively. The loading experimental conditions also greatly affect the solid–solid interactions of transition metal-zeolites at elevated temperatures. ZnAl2O4 and silica phases were formed upon thermal treatment of Zn–Y zeolites. The ratio of ZnAl2O4 to silica phases increases as the amount of loaded Zn2+ increases in the corresponding unheated zeolites. However, nepheline phase was obtained upon heating Fe–Y zeolites loaded at low initial Fe2+ concentrations. Upon increasing of loaded Fe2+, iron oxide beside other amorphous phases from silica, alumina and/or aluminosilicates were obtained.

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