Dehydroaromatization of methane over Mo/ZSM-5 zeolites: influence of aluminum distribution in the crystals

HORŇÁČEK, Michal – HUDEC, Pavol – JORÍK, Vladimír – ČAPLOVIČOVÁ, Mária – ČAPLOVIČ, Ľubomír – KALIŇÁK, Michal – SMIEŠKOVÁ, Agáta


Mo/ZSM-5 type catalysts based on two ZSM-5 zeolites with comparable crystal morphology, shape and size, Si/Al in bulk (22–23), acidity and amount of Mo (~ 4.7 wt.%) but having a different (homogeneous and non-homogeneous) Al distribution in particles and different acid sites type distribution were investigated in methane dehydroaromatization. From the results follows that Mo is associated with both BAS and LAS in the samples with almost homogenous Al distribution (MoZSM-5/AH). In the case of both samples with non-homogenous Al distribution (MoZSM-5/BH and MoZSM-5/BNH4) Mo preferably associates with BAS. Evidently lower activity and selectivity of Mo/ZSM-5/AH catalyst in methane transformation compared with Mo/ZSM-5/BH we attribute to the fact that from Mo species which interact with Lewis acid sites in sample ZSM-5/AH less active carburized species are formed as from the Mo associated with Brønsted sites in sample ZSM-5/BH.