Conversion of Light Alkanes Into Aromatic Hydrocarbons. 3. Aromatization of Propane and Propene on Mixtures of HZSM5 and of Ga2O3

Abstract

The activities for propane aromatization of physical mixtures of HZSM5 (25 mg) and Ga2O3 (5 to 200 mg) are much greater than the sum of the activities of the pure components. This synergic effect is characteristic of a reaction in which catalytic sites of the two components (bifunctional catalysis) participate. Experiments with model reactants propane, propene, 1-hexene, 1-heptene, methylcyclohexene and methylcyclohexane confirm that gallium oxide catalyzes the dehydrogenation of alkanes into olefins and of naphthenes into aromatics but is not active for oligomerization and cyclization reactions. The aromatization of propane on the mixture occurs in the following way: on gallium oxide propane is dehydrogenated into propene; propene diffuses from gallium oxide to HZSM5, on which it undergoes oligomerization and then cyclization; naphthenic compounds diffuse from HZSM5 to gallium oxide where they are dehydrogenated into C6-C8 aromatics.