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We used resonant ultrasound spectroscopy to measure the three independent elastic constants of PdH0.71and PdH0.65in the temperature range 1.4 K < T < 296 K. Measurements were performed as the crystals were rapidly cooled (~10 K min- 1) and then slowly heated (~0.1 K min- 1). During slow heating, the temperature dependence of the shear modulus C' = (C11– C12)/2 shows a small peak at ~55 K, but this peak is absent during fast cooling. We associate the peak with the so-called “50 K anomaly” in palladium hydride. In contrast, the other shear modulus, C44, shows no peak during slow heating. We propose that the 50 K anomaly observed in the elastic constants, and in other thermodynamic and transport properties of Pd-hydride, is a kinetic effect arising from changes in the hydrogen atom short-range order as the alloy is heated.

Light olefins and paraffins are commonly separated by cryogenic distillation. A process based upon reversible chemical complexation, which employs a mass-separating agent rather than an energy-separating agent, presents an attractive alternative to distillation. Use of such a facilitated-transport-assisted process could substantially reduce the capital costs and energy requirements of olefin/paraffin separations. Copper(I) and silver(I) have long been known to form electron donor/acceptor complexes with olefins. Several chemical systems using these transition metals as the selective separating agent have been studied. A review of copper- and silver-based complexing solutions for olefin/paraffin separations via gas/liquid contacting is presented.