ON THE REACTIVITY OF H-MFI, GA-MFI AND CU-MFI ZEOLITES TOWARDS T-BUTYL HYDROPEROXIDE (TBHP)

The highly acidic H-MFI zeolite effectively catalyzes the decompositio n reaction of t-butyl hydroperoxide (TBHP) which most likely proceeds through an electrophilic attack of the zeolite protons on either oxyge n of the peroxide. Replacement of the zeolitic protons by cationic Ga leads to a decrease of the reaction rate due to the removal of proton sites which also suggests that gallium cations are virtually inactive for TBHP decomposition. In contrast, copper ion-exchanged MFI is an ac tive TBHP decomposition catalyst and, more importantly, radicals are i nvolved as intermediates in the decomposition mechanism. The existence of radicals in the liquid phase was unambiguously evidenced utilizing N-phenyl-beta-naphthylamine as a radical inhibitor in the batch react ion. The involvement of a homolytic pathway in the decomposition react ion is explained with oxidation-reduction cycles of the zeolite copper cations.