13C MAS NMR mechanistic study of the initial stages of propane activation over H-ZSM-5 zeolite

C-13 MAS NMR study of the early stages of propane 2-C-13 activation was performed over H-ZSM-5 catalysts with various content of protonic and aprotonic sites. The reaction mechanism was tested by addition of various probe-molecules (C3H6, C6H6, H-2, H2O and CO). The results on tracing the fate of 13C label during this experiments conclude to a monofunctional mechanism involving propane protonation on the strong Bronsted sites of H-ZSM-5 and the formation of carbonium ion type transition states, which further evolve in four different ways leading to C-13 scrambling in propane, cracking, dehydrogenation and disproportionation.