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

Authors: Ivanova I.I.¹; Pomakhina E.B.²; Rebrov A.I.²; Derouane E.G.³

Source: Topics in Catalysis, Volume 6, Numbers 1-4, 1998 , pp. 49-59(11)

Publisher: Springer

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Abstract:

^{13}\mathrm{C} MAS NMR study of the early stages of propane 2-^{13}\mathrm{C} 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 (\mathrm{C}_{3}\mathrm{H}_{6}, \mathrm{C}_{6}\mathrm{H}_{6}, \mathrm{H}_{2}, \mathrm{H}_{2}O and CO). The results on tracing the fate of ^{13}\mathrm{C} label during this experiments conclude to a monofunctional mechanism involving propane protonation on the strong Brønsted sites of H-ZSM-5 and the formation of carbonium ion type transition states, which further evolve in four different ways leading to ^{13}\mathrm{C} scrambling in propane, cracking, dehydrogenation and disproportionation.

Keywords: propane activation; mechanism; zeolites; H-ZSM-5; MAS NMR; carbenium ions; carbonium ions

Language: English

Document Type: Regular paper

Affiliations: 1: Moscow State University, Department of Chemistry, Vorobievy Gory, 119899 Moscow, Russia 2: Institute of Petrochemical Synthesis, RAS, Leninsky pr. 29, 117012 Moscow, Russia 3: The University of Liverpool, The Leverhulme Centre for Innovative Catalysis, PO Box 147, Liverpool L69 3BX, UK

Publication date: 1998-01-01