Capturing low-pressure hydrogen using V-Ti-Cr catalyzed magnesium hydride

Catalyzed magnesium hydride is suggested as a potential absorbent material for hydrogen separation, purification, and other relevant applications. The present study reports an investigation on selective hydrogen absorption using ball-milled VTiCr-catalyzed MgH2 from a gaseous mixture. Temperature oscillation absorption method, thermogravimetric analysis and differential scanning calorimeter techniques are utilized to characterize the VTiCr-catalyzed MgH2, demonstrating a reversible capacity up to 4 wt%H when the temperature is oscillated between 150 and 350 degrees C. When the hydrogen partial pressure is increased from 0.04 to 0.4 bar the reaction (dehydrogenation and hydrogenation) temperatures increase, and so do the reversible hydrogen capacities. The reaction kinetics are stable during the first 10 cycles. Transmission electron microscopy analysis shows that the VTiCr catalyst is a few nanometers in size and is dispersed uniformly in MgH2 matrix. The results of this study demonstrate that nano-VTiCr catalyzed MgH2 can readily react with low-pressure hydrogen and cycle in the mixture atmosphere.