A Quantitative Analysis of the Hydrogen Sorption Isotherms of MmNi4.25Al0.75.

The development of materials for hydrogen thermal compression should follow minimalistic and ecological aspects including low energy consumption, low-cost unitary operation production and low waste generation. These concepts are applied in this work by applying models previous to measurements in devices. The results include the application of a quantitative model to measurements of hydrogen sorption properties of an intermetallic of composition MmNi4,25Al0,75, synthesized by low energy reactive milling. The intermetallic was annealed in Ar at 600 °C for 24 h to improve the microstructural properties. The samples were analyzed in a Sievert's-type device. Curves of pressure vs. composition were previously obtained in a temperature range between 25 °C and 100 °C. A modeling of PCT curves was done. Two different stages were analyzed. The parameters involved in the model correspond to thermodynamic properties ΔHf y ΔSf of hydride formation. These results are used in the design of a one-stage hydrogen thermal compressor.