Reactivities and properties of lanthanide catalysts prepared by thermal degradation of liquid ammonia solutions of Eu or Yb metal

Studies of X-ray diffraction, Fourier-transform infrared spectra and catalytic properties of lanthanide catalysts (Eu/AC and Yb/AC) prepared by impregnation of active carbon (AC) with liquid ammonia solutions of Eu or Yb metal were carried out for the catalytic hydrogenation of ethene. The lanthanides thus deposited on AC were changed through varied steps (metal, amide, imide or nitride) by thermal treatments and simultaneously the hydrogenation activity varied markedly. Eu/AC and Yb/AC which were subjected to the evacuation treatment around 573 and 773 K, respectively, showed a high activity even at 203 K. The catalytic properties of lanthanide amide (Eu(NH2)(2), Yb(NH2)(2), and Yb(NH2)(3)) prepared separately, imide and nitride were investigated for comparison. It was concluded that imide or imide-like species formed during the thermal decomposition processes of europium(II) and ytterbium(II and III) amides to nitride at 503-573 and 423-773 K was active catalysts for Eu/AC and Yb/AC, respectively.