Initial activity/selectivity of H-Gallosilicate (MFI) in propane aromatization: influence of H⁺ exchange and thermal/hydrothermal pretreatments

Abstract

Initial activity/selectivity of H-gallosilicate (MFI) zeolite with different degrees of H⁺ exchange and pretreated under different thermal and hydrothermal conditions in propane aromatization (at 500≠ C) has been determined using a pulse microreactor connected to GC. It is found to be strongly influenced by the degree of H⁺ exchange, calcination temperature and hydrothermal treatment at different temperatures and concentrations of steam. There exists a close relationship between the acidity (measured in terms of pyridine chemisorbed at 400≠C) of the gallosilicate and its initial propane conversion and aromatization activity. Presence of strong acidic sites (attributed to FW Ga) at high concentration is essential for the well dispersed non-FW Ga oxide species to be active for dehydrogenation in the propane aromatization over the zeolite.