Hydride alloys properties investigations for hydrogen sorption compressor

The use of metal hydride technology in hydrogen compression applications requires thorough knowledge of important thermophysical and sorption properties of selected hydrogen absorbing alloys. Three intermetallics, LaNi4.8Sn0.2, LmNi4.9Sn0.1 and MmNi4.7Al0.3 were selected among various alloys of the AB5 family for use in a thermal hydrogen compressor and allow us to reach an outlet pressure of 20 atm. In this context, pressure-composition isotherms (PCT) at various temperatures included in the thermal operation range of the compressor were measured for the three alloys. Differential scanning calorimetry was used to determined their specific heats and effective thermal conductivities. A LaNi4.8Sn0.2 sample was also cycled 1000 times to test for its long term stability, and no significant change in sorption properties was detected, except for a small decrease of 0.05% hydrogen weight in total capacity and a small hysteresis reduction.