C-H bond activation of propane on Ga2O22+in Ga/H-ZSM-5 and its mechanistic implications
Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga2O22+stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga2O22+spe-cies corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga2O22+species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga2O22+species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga2O22+species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga2O22+species corresponding to GaHHW.
Propane dehydrogenationGa2O22+Activation of C-H bondGa species
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