AROMATIZATION OF N-HEXANE OVER GALLOALUMINOSILICATE AND GALLOSILICATE

It is shown that proton forms of galloaluminosilicate and gallosilicate exchanged with ammonium nitrate solution have much higher activity for the aromatization of n-hexane than Ga3+-exchanged H-ZSM-5 or Ga2O3-supported H-ZSM-5. This can imply that a large amount of gallium species are uniformly introduced into zeolite crystallite of galloaluminosilicate and gallosilicate, which promote the dehydrogenation of n-hexane to hexene. On the other hand, a proton form of gallosilicate exchanged with hydrochloric acid shows lower activity for the aromatization of n-hexane, but the activity of the proton form of gallosilicate is increased by a small addition of Ga3+. It is suggested that active gallium species over galloaluminiosilicate and gallosilicate are not gallium species in the framework but those outside the framework.