Abstract :
The hydriding and dehydriding properties of
the tetrahydrofuran (THF) treated magnesium, along
with its electronic energy states, crystalline structure
and micro morphology have been investigated. The
THF treated magnesium absorbs 6.3 wt% hydrogen at
723 K and 3.5 MPa. After hydrogenation, in addition to
the expected hydride MgH2, a new less-stable hydride
phase appears at 673 K, but not at a lower temperature.
Desorption produces 5.5 wt% hydrogen at 723 K
against a back-pressure of 1.3 Pa after 20 cycles of
hydriding–dehydriding. The THF treatment improves
the kinetics of hydrogen absorption and desorption.
The THF treated Mg exhibited reasonable reaction
rates with hydrogen at 623 K. XPS (X-ray Photo-electron
Spectroscopy) studies show that THF treatment
causes the electronic energy state of the magnesium
atoms to shift, but the XRD (X-Ray Diffractometer)
studies show the crystal structure remains unchanged. It
is believed that the chemical state of magnesium surface
is activated by THF treatment in favor of hydrogen
absorption and desorption. Metallographic observation
of the magnesium hydrides reveals some interesting
features during hydrogenation.
