Study of n-octene aromatization over nanoscale HZSM-5 zeolite

Influence of space velocity and acidity of HZSM-5 zeolite on the aromatization of n-octene over nanoscale HZSM-5 has been investigated at 350 and 400 degrees C. The distribution of aromatics is strongly influenced by the space velocity and the amount of the strong acid sites of the catalyst. The results show toluene and C-8 aromatics are the most significant aromatics products while the formation of benzene is less rapid during the aromatization of n-octene over the nanoscale HZSM-5 zeolite. Due to the high steric hindrance in the ZSM-5 channels, C-9 aromatics are formed in the external surface of the nanoscale HZSM-5 zeolite. With the decrease of the space velocity, the selectivities of benzene and toluene increase while those of C-8 and C-9 aromatics decrease. The decrease of the amount of the strong acid sites results in the decrease of the concentrations of C-6 and C-7 carbenium ions and the increase of those of C-8 and C-9 carbenium ions. Consequently, the decrease of the amount of the strong acid sites leads to the decrease in the formation of benzene and toluene and the increase in that of C-8 and C-9 aromatics. (C) 2008 Elsevier Inc. All rights reserved.