Nuclear magnetic resonance of hydrogen sorbed by powdered palladium metal and alumina-supported palladium.

Hydrogen in 0.2 micron beta-palladium powder and in an alumina-supported palladium catalyst was investigated by NMR spectroscopy. The dependence of the shift on hydrogen pressure and the hydrogen-to-palladium (H/Pd) ratio in beta-palladium hydride was determined for 273 K < T < 368 K. The activation energy for the process affecting the hydrogen shift is 9.4(+/- 0.5) kcal mol-1, similar to the enthalpy of transition from the alpha- to beta-phase. NMR measurements of hydrogen in alumina-supported palladium show a similar behavior, which may allow one to use NMR shifts as a barometer of the state of the hydrogen in the metal.