Unraveling Hydrocarbon Pool Boosted Propane Aromatization on Gallium/ZSM-5 Zeolite by Solid-State Nuclear Magnetic Resonance Spectroscopy

Propane aromatization on metal-modified zeolites provides a promising route to produce valuable chemicals such as benzene, toluene and xylene via non-petroleum feedstocks. The mechanistic understanding of propane conversion to aromatics is still challenging due to the complexity of the aromatization process. Herein, by using solid-state NMR spectroscopy and GC-MS, it is shown that cyclopentenyl cations are formed as active intermediates during propane aromatization on Ga/ZSM-5 zeolite. Autocatalysis of propane to aromatics is identified in the induction period. The cyclopentenyl cations serve as key hydrocarbon pool species to co-catalyze propane conversion and promote aromatics formation, revealing a dominant hydrocarbon pool process in propane aromatization.