Palladium, Yttrium, Copper Ternary Alloys for Hydrogen Purification

Palladium has long been recognised for its hydrogen sorption and separation capabilities. Alloying with different metals to produce binary alloys has been shown to further improve many of its essential properties significantly. Currently palladium-silver alloys are used commercially for the hydrogen purification process, however, other binary alloys have also been shown to significantly improve the hydrogen sorption properties (palladium-yttrium), and palladium’s resistance to poisoning by hydrogen sulphide (palladium-copper). Whilst a number of binary palladium alloys have previously been investigated none has shown all the required target properties for an effective hydrogen purification membrane as set by the US DoE . This work will study a number of palladium, yttrium, copper, ternary alloys of varying copper compositions, and investigate their characteristics as a suitable hydrogen purification material. The produced membranes, will be characterised using X-ray diffraction, scanning electron microscopy, hardness measurements, and the use of a confocal microscope and then tested using a hydrogen flow rig, to determine their suitability as a hydrogen purification material. Results showed that the addition of a small amount of copper to a Pd-8at%Y alloy leads to marked changes in a number of key alloy parameters relevant to membrane performance. The lattice parameter was increased, as was hydrogen flow, and materials hardness, whilst average grain size was reduced. ii Acknowledgements Firstly I would like to thank the EPSRC for making the funding available for me to complete my course Secondly I would like to thank both David Book and John Speight for there supervision, support and guidance throughout my time studying. Thanks to Sean Fletcher for his time and help to me throughout my studies, and to the many others from the department that have offered guidance to me throughout my work. Many thanks must also go to my parents and sister, who encouraged me to return to studying and follow this interest, and have continued to support me throughout the year of study and time writing up. And finally many thanks to the friends I have made both in the lab and the Department that helped make the year so enjoyable.