Mechanism of butane transformation

Catalytic activity and aromatic selectivity of n-butane transformation were studied over various MFI type zeolites. From the data obtained, a reaction mechanism is suggested for different catalyst systems. It is visualized th at in gallium doped catalysts, Ga3+ directly takes part both in cracking an d dehydrogenation. The [Ga CH3](2+) and [GaH](2+) species formed during cra cking and dehydrogenation require protonic sites for regeneration of Ga3+ s pecies. An alternative mechanism was suggested for dehydrogenation and crac king by Ga3+ without the involvement of protonic sites. However a protonic site would be required for aromatization. In case of gallosilicates a one s tep mechanism is suggested for cracking and dehydrogenation reaction which does not require the presence of protonic sites in the catalyst system.