1H-31P HETCOR NMR elucidates the nature of acid sites in zeolite HZSM-5 probed with trimethylphosphine oxide

Two-dimensional H-1-P-31 heteronuclear correlation NMR of trimethylphosphine oxide (TMPO) adsorbed in zeolites, in tandem with DFT calculations, challenges previous one-dimensional P-31 NMR assignments, enabling the unambiguous discrimination of Bronsted and Lewis acid sites, extending the understanding of TMPO:Bronsted complexes formed with distinct stoichiometries at the HZSM-5 zeolite surface, and the proton-transfer mechanism.