Aromatization of butane over modified mfi-type zeolite catalysts

Abstract The aromatization of butane on zinc modified HZSM-5 and gallum-and/or copper-modified HZSM-5 was studied. The activity, selectivity and thermal stability of the Zinc-modified catalysts prepared by various methods were discussed. The zinc loaded on HZSM-5 by the impregnation showed the highest activity. However, at a reaction temperature higher than 873K this catalyst lost part of the zinc from the zeolite surface. On the other hand, the zinc loaded into the zeolite framework showed relatively low activity and selectivity to aromatics donation, but it showed relatively high thermal stability. The gallium loaded on copper partially ion-exchanged HZSM-5 by impregnationshowed high selectivity for aromatics donation., It is concluded that in this catalyst, gallium promotes dehydrogenation including the initial conversion of butane and the reaction step from C 6 -C 9 olefin to aromatics. The copper ion mainly controls the acidity of the HZSM-5 to depress the cracking of the butane and C 6 -C 9 olefins.