Fuel, Vol.236, 1293-1300, 2019
Tuning the acidity and reducibility of Fe/ZSM-5 catalysts for methane dehydroaromatization
Methane dehydroaromatization was studied over Fe/ZSM-5 promoted catalysts. Transitions metals (Cu, Ni, Co, and Zn) were used as promoters aiming to alter the Fe reducibility whereas alkali metals (Ca, Mg, and La) were used with the purpose of decreasing the acidity of ZSM-5. The samples were characterized by surface area measurements (S-BET), TPR, XRD, TPD-NH3 and TPO. Activity tests were carried out at 750 degrees C in a fixed-bed quartz tubular reactor with on-line GC analysis. The addition of transition metal or alkali metal to Fe/ZSM-5 alters to a greater or lesser extent both the reducibility and the acidity of the catalyst. Among the transition metals, Cu-promoted catalyst showed a shorter induction time and high rate of benzene formation. Among the alkali metals, Ca-promoted catalyst produced a significant decrease in coke formation and formed significant amounts of aromatics.
Keywords:Methane dehydroaromatization;Fe/ZSM-5 catalysts;Acidity strength;Fe reducibility;Coke formation