Adsorption, desorption, and interparticle motion of hydrogen on silica‐supported ruthenium: A study by in situ nuclear magnetic resonance

摘要: 1H NMR line shapes of hydrogen adsorbed on silica‐supported ruthenium at pressures 10−6–10 Torr were studied by using selective excitation via DANTE sequences. A transition from inhomogeneous to homogeneous broadening was observed coverage ∼0.5. The spectra simulated generalized Bloch equations that included N‐site exchange processes. shape originates increased mobility, whereas proton–proton dipolar couplings are negligibly small. rate parameter k obtained this model quantifies the average mobility in process. This increases more than three orders magnitude when changes 0.4 0.8. simulations variable temperatures showed exhibits Arrhenius behavior with an activation energy 52 (±5) kJ/mol and preexponential factor k0=4×1010 s−1. It is implied motion must involve desorption, interparticle diffusion,...