Adsorption of Trimethylphosphine Oxide Molecules from the Gas Phase to Probe Surface Acidity by Solid-state NMR

Trimethylphosphine oxide (TMPO) molecules were adsorbed on H-type mordenite to probe the surface acidity by solid-state NMR. We found that dichloromethane was coadsorbed when it was used as a solvent. To avoid the effect of the solvent, TMPO was adsorbed from the gas phase, and we have obtained 1H and 31P magic-angle-spinning (MAS) NMR spectra of TMPO-adsorbed H-type mordenite without the effect of the solvent.