Multiple-pulse 1H nuclear magnetic resonance investigations of titania and ruthenium dispersed on titania
Abstract
1 H NMR spectra of Ru/TiO2 and TiO2 consist of sharp and broad resonances associated with the oxide support and hydrogen chemisorbed on ruthenium particles. The cause of the line broadening has been investigated using pulsed NMR techniques. Line-narrowing is not observed for these samples under multiple pulse (MREV8) decoupling. Selective excitation (DANTE) of the TiO21H NMR spectrum shows that the linewidth arises from a distribution of chemical shifts and not from static homonuclear 1H dipolar coupling at 370 K. The 1H NMR results imply that the hydrogen species in these catalyst systems are labile on the NMR spectral timescale.