Oxydehydrogenation of Ethane and Propane over Alkaline Metal Modified Fe-ZSM-5 Zeolites

Iron modified zeolites of MFI structure, calcined at 873 and 1173 K, were doped with sodium cations in amounts corresponding to 1/4, 1/2, 3/4 and to the total number of acidic centres, estimated from TPD of ammonia. Sodium modified Fe-ZSM-5(900) gradually lost their oxidative activity with an increase in the concentration of alkaline cations, while the activity of Na/Fe-ZSM-5(600) changed slightly and diminished considerably only after significant removal of acidic centres. The results of propane ODH reaction, performed at different contact times over alkaline free and alkaline modified Fe-ZSM-5 indicated, that oxydehydrogenation and cracking reactions on the samples calcined at 1173 K occurred as consecutive reactions, while in the presence of catalysts activated at 873 K, and characterised by strong acidic centres, both reactions occurred simultaneously.