Characterization of LaNi4.70Al0.30 handled in air and application to a scheme of thermal compression of hydrogen

Abstract

LaNi4.70Al0.30 was characterized by SEM, EDS and XRD. The structure was refined by theRietveld method. The intermetallic stability temperature range in air was analyzed by DSC.The intermetallic is destabilized at T > 160 C. The intermetallic was annealed at thistemperature for 24 h in air. After that, the pressure-composition-isotherms weremeasured. The thermodynamic properties were calculated from the Van´t Hoff diagrams.Values obtained were DHf ¼ 30 2 kJ/mol and DSf ¼ 0.13 0.01 kJ/mol for absorption process and DHd ¼ 31 2 kJ/mol and DSd ¼ 0.14 0.01 kJ/mol for desorption process.From these results, a scheme of thermal compression of hydrogen (TCH) was proposed.The scheme has a practical compression ratio (Rc) of 7.2 in the 25 to100 ºC temperaturerange and 1 to 1000 kPa pressure range.