Suitability of using ZSM-5 over other medium pore zeolites for n-hexane aromatization — a density functional study

Abstract

The aromatization of n-hexane over medium pore zeolites e.g. ZSM-5, ZSM-22 and EU-1, has been studied using density functional theory (DFT). We compared the activities of different T sites present in these three zeolites and located the active T sites as T6 (ZSM-5), T4 (ZSM-22) and T8 (EU-1), respectively, by correlating the geometric parameters such as bond length and bond angles with electronic properties. The experimental Brønsted acidity order has been compared with our calculated deprotonation energy to validate our model. Now, to choose the best zeolite among the three zeolites studied in terms of activity toward aromatization, we have performed DFT calculations on the organic molecules (both reactant and major products), zeolite cluster and zeolite organic molecule complex. The result matches the experimental observation by justifying the suitability of ZSM-5 in aromatization reaction in comparison to other medium pore zeolites.