EXCELLENT CATALYTIC AGENT CONSISTING OF LEACHED QUASICRYSTAL FOR HYDROGEN SORPTION IN MGH2

摘要

The hydrogen sorption characteristics of Magnesium Hydride (MgH2) have been performed with a leached Al-Cu-Fe quasicrystal (as cast and mechanically activated) for the first time. The ball-milled Al-Cu-Fe quasicrystal reveals excellent catalytic activity, after leaching treatment. The onset desorption temperature of MgH2 catalyzed with leached mechanically activated Al-Cu-Fe quasicrystal has reduced drastically to -2 1 O°C and faster rehydrogenation kinetics by absorbing -6 wt. % of H2 in just 30 seconds under 20 atm H2 pressure at 250°C. Dehydrogenation kinetics under latm H2 pressure is found to be -6.2 wt. % in -2.9 minutes. Novel reabsorption upto 6 wt.% within 30 seconds at 250°C has been obtained. Improved rehydrogenation kinetics has been observed even at lower temperatures of 100°Can d 150°C by absorbing - 5 wt. % in 30 minutes and 5.5 wt. % within 1 minute under the same condition of H2 pressure. The activation energy has been found to be - 35.75 and 64.25 kJ mol-" using Johnson-Mehl-Avrami model for absorption and desorption respectively, whereas change in enthalpy in Vant"s Hoff plot has been found to be - 71.12 and 73.66 kJ mol-1.