Conversion of alcohols to aromatics on H-SM-5: influence of Si/Al ratio and degree of cation exchange on product distribution

Abstract

The extent of aromatization and the distribution of aromatic hydrocarbons in the conversion of methanol and ethanol on H-ZSM-5 have been found to be strongly dependent on the Si/Al ratio and the degree of H-exchange of the zeolite. The aromatization activity in both the alcohol conversion reactions decreases with the Si/Al ratio and increases with the degree of H⁺-exchange. The reactions on H-silicalite yield mostly aliphatic hydrocarbons. An appreciable extent of hydrocarbon residue is retained in the zeolite channels for both the reactions on H-silicalite and on the zeolites with lower degrees of H⁺-exchange. The strong acid sites are required for the aromatization and in their absence, the deposition of hydrocarbon residue in the zeolite channels occurs. A good correlation between the acidity (active acid sites) and the aromatization activity of the zeolite has been obtained.