ABSTRACT The effect of reaction atmosphere on selectivity and ageing has been investigated in aromatization of n-hexane over ZnO-supported H-ZSM-5 (ZnO/H-ZSM-5), galloalumino-silicate (Si-Al-Ga) and H-ZSM-5. Though the initial yield of aromatics over ZnO/H-ZSM-5 and Si-Al-Ga became lower as a hydrogen pressure in the reaction was higher, it was found that hydrogen reduces the rate of deactivation of Si-Al-Ga. It was suggested that zinc and gallium species can catalyze hydrogenation of lower olefins and dealkylation of aromatics. Furthermore, it was found that gallium species can inhibit coking on acid sites by activating hydrogen as well as VIII group metals.
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