Hydrogen sorption by a supersaturated solution of carbon in palladium

The phase transitions occurring during the acetylene hydrogenation reaction of a palladium catalyst containing up to 13% C have been studied by X-ray diffraction. The hydrogen desorption isotherms for PdC and Pd have been obtained using volumetric apparatus. A solid solution of composition PdC0.13 had no tendency to form the β-hydride phase, unlike pure Pd. Solutions with lower carbon content showed decreasing tendency to form the β-hydride phase, as shown by the shorter plateau section of the isotherm and the decrease in the hysteresis of the PdH system.