Platinum Group Metal Hydrides
Platinum Group Metal Hydrides
Their Properties and Applications Considered
Conferences on hydrogen energy and metal-hydrogen systems continue to include significant numbers of contributions concerning hydrides of palladium and other platinum group metals. This article reviews some of the relevant papers presented recently at Colorado Springs.
A continuing worldwide interest in hydrogen as an economically important source of energy has been reflected in the series of World Hydrogen Energy Conferences (1). Papers concerning metal-hydrogen systems included in these conference programmes have had particular general reference to the aspects of hydrogen embrittlement and of hydrogen storage in metallic hydrides. Some of the more recent conferences (2, 3, 4), which have been specifically concerned with metal-hydrogen systems, have also been largely centred around one or other of these subject areas. The most recent of these has been an International Symposium on the Properties and Applications of Metal Hydrides, held in Colorado Springs, U.S.A. during April 1980. However, as in the other conferences, a significant proportion of papers dealt with the hydrides of the platinum metals or their alloys.
In the area of thermodynamic and structural studies, further calorimetric measurements of heats of absorption of hydrogen by palladium, combined with pressure-composition (p-c) relationships were reported by T. B. Flanagan, B. S. Bowerman, C. A. Wulff and G. E. Biehl, of the University of Vermont, and p-c relationships determined with thin palladium films in conjunction with measurements of their electrical resistivities by G. A. Frazier and R. Glosser, of the University of Texas at Dallas. Possible effects of local differences of surface hydrogen chemical potential on palladium cathodes were discussed by F. A. Lewis, of the Queen’s University of Belfast, with reference to electrolytic hydrogen isotope separation factors and isotope exchange reactions. Measurements of hydrogen solubilities in some palladium intermetallics were reported by A. J. Maeland and G. G. Libowitz, of Allied Chemical Corp., Morristown, U.S.A. The formation of a hydride of rhodium as part of a programme of studies at pressures up to 70 kilobars and 750 K was reported by E. G. Ponyatovsky, V. E. Antonov and I. T. Belash, U.S.S.R. Academy of Science, Chernoglovska. Correlations of hydride formation with electronegativities, electronic structure and chemisorption characteristics were outlined by J. W. Ward of the Los Alamos Scientific Laboratory.
E. Wicke of the University of Münster discussed measurements made at low temperatures of magnetic susceptibility, electronic specific heat and Mössbauer spectra in the palladium-ruthenium-hydrogen system, while evidence from Mössbauer spectroscopy of the hydrogen environment around substitutional rhodium, ruthenium, cobalt and iron in β -phase palladium hydride was reported by F. E. Wagner, M. Karger, and F. Pröbst, of the Technical University of Munich. NMR studies of hydrided rhodium intermetallics were reported by T. C. Jones, T. K. Halstead and K. H. J. Buschow, of the Universities of York and Eindhoven. Measurements of the variation of the temperature of the superconducting transition with silicon content in the palladium-silicon-hydrogen (deuterium) system were presented by B. Stritzker and H. L. Luo, KFA Jülich, Germany and University of California; speculations concerning superconductivity in the platinum-hydrogen system were advanced by D. A. Papaconstantopoulos, Naval Research Laboratory, Washington. Studies of elastic energy dissipation effects related to hydrogen mobilities, which had been measured over a wide range of hydrogen contents in the palladium-hydrogen system, were reported by F. M. Mazzolai, P. G. Bordoni and F. A. Lewis of the Istituto di Acustica, Rome and Belfast.
The permeation of hydrogen through membranes of palladium and palladium alloys continues to be actively investigated. Effects of cold-rolling on the diffusion of tritium through palladium were reported by B. Huber and G. Sicking of the University of Münster. Influences of hydrogen solubilities on permeation through palladium-rare earth alloys were discussed by D. T. Hughes of the U.K. Electricity Council Research Centre, J. Evans and I. R. Harris, of the University of Birmingham, England, and the efficiencies of palladium overlayers in promoting hydrogen uptake into niobium and tantalum by M. A. Pick, M. Strongin and M. G. Greene, of the Brookhaven National Laboratory, U.S.A. Apparently extensive studies by E. M. Savitsky and other Russian workers were reported in abstract, concerning the use of membranes of palladium alloyed with ruthenium, rhodium, nickel and copper as hydrogenation catalysts. High efficiencies and selectivities were claimed.
Papers presented at the symposium will be published later this year in the Journal of Less-Common Metals.
Third World Hydrogen Energy Conference Tokyo 23–26 June 1980
Platinum Metals Rev., 1976, 20, (2), 54; 1977, 21, (4), 134; 1979, 23, (3), 99
Hydrides for Energy Storage, (Symp. at Geilo), ed. A. F. Andresen and A. J. Maeland, Pergamon Press, 1978
Proc. Second Japan Inst. Met Symp. Hydrogen in Metals, Suppl. Trans. Jpn. Inst. Met., Vol. 21, 1980