A novel peroxy radical species formed in Na+/Y zeolites upon interaction with hydrogen peroxide: A CW-EPR study

A peroxy radical species is generated in the framework of Na+/Y zeolites, upon treatment with a hydrogen peroxide solution, drying and evacuation of the solid at 420 K. The amount of the species increases upon increasing the temperature of the treatment under vacuum up 570 K. The EPR spectrum of the species at 77 K is characterized by anisotropic g tensor (g(1) = 2.059, g(2) = 2.010, g(3) = 2.007). Upon increasing the recording temperature the spectrum undergoes a dramatic evolution indicating the onset of motional phenomena. This dynamic behavior together with the values of the g tensor components and the high thermal stability of the species allow one to distinguish the observed species rom the more common superoxide radical ion produced by oxygen adsorption on Na+/Y zeolites treated with metallic sodium.