Dynamic measurements of hydrogen reaction with LaNi5−xSnx alloys

Abstract The study focuses on the reaction between hydrogen gas and LaNi 5− x Sn x alloys, where 0 ≤  x  ≤ 0.5, in broad temperature and pressure ranges. It was performed by means of dynamic volumetric techniques using specific equipment developed at our laboratory. The substitution of Ni by Sn lowers the system equilibrium pressure and increases the hydrogen absorption reaction rate. Reaction pressures at room temperature range from 8 kPa ( x  = 0.5) to 250 kPa ( x  = 0). At 415 K the reaction pressure is within the range from 200 kPa to 4000 kPa for x  = 0.5 and 0, respectively. The measured characteristic absorption time at 750 kPa for LaNi 5 is around 1 min, while it remains below 2.5 s for LaNi 4.5 Sn 0.5 . The maximum H concentration goes from 1.3 wt.% for LaNi 5 down to 0.95 wt.% for LaNi 4.5 Sn 0.5 . These results are useful to identify a metal system where the hydrogen interaction equilibrium properties can be tuned in a wide pressure range by choosing the chemical composition and the process temperature.