Hydrogen-desorbing behavior of the hydrides in 15 rare earth elements measured by temperature swing column chromatography

Abstract

Hydrogen-desorbing behavior of the hydrides in 15 rare earth elements (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) was examined by temperature swing column chromatography from room temperature to 1273 K. As a result, it was found that hydrogen-desorbing profiles of the rare earth hydrides except Eu had two peaks. The first peaks were located on low-temperature zone of about 600–700 K, the second peaks were located on high-temperature zone of about 700–900 K, and the peaks were separated. The cause of separation was the bonding type between hydrogen and metals, not from hetero-reaction of dehydrogenation. The bonding between hydrogen and metals seemed to be two types. In addition, the first peaks had two types, sharp one and broad one. The first peaks of Y and heavy rare earth Tb–Lu showed sharp one and those of light rare earth La, Ce, Pr, Nd showed broad one. Sm, Eu and Gd showed complex hydrogen-desorbing behavior. Molar ratio of the first bonding hydrogen atom dissociated at low-temperature zone to the second bonding hydrogen atom dissociated at high-temperature zone was approximately 1–2.