Conversion of light alkanes into aromatic hydrocarbons: 1-dehydrocyclodimerization of propane on PtHZSM-5 catalysts

Abstract

Conversion of propane into aromatic compounds (dehydrocyclodimerization) was studied at 530°C on a series of PtHZSM-5 catalysts with different platinum contents. For this reaction, occurring via propene, the product distribution and its change with the conversion rate were compared with those in the conversion of propene on HZSM-5. Large differences were observed; in particular, the selectivity for C 6 C 8 aromatic products was greater on PtHZSM-5 than on HZSM-5 whereas the selectivity for C 4 and non-aromatic C 5+ was lower. These differences can be explained by the significant increase in the aromatization rate of aliphatic C 6+ intermediates, dehydrogenation on the platinum sites being faster than hydrogen transfer on the acid sites. Moreover, a higher production of methane and ethane is observed on PtHZSM-5 catalysts owing to the hydrogenolysis of alkanes and of alkylaromatic products on the platinum sites.