Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium

Journal Article · Tue May 25 04:00:00 EDT 2004 · Journal of Alloys and Compounds

OSTI ID:824530

AU, MING

The electronic structure, crystalline feature and morphology of the tetrahydrofuran (THF) treated magnesium, along with its hydriding and dehydriding properties have been investigated. The THF treated magnesium absorbs 6.3 wt per cent hydrogen at 723K and 3.5 MPa. After hydrogenation, in addition to the expected MgH2, a new less-stable hydride phase appears at 673K, but not at a lower temperature. Desorption produces 5.5 wt per cent hydrogen at 723K 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 significantly. From 723K to 623K, the THF treated Mg demonstrates acceptable reaction rates. XPS studies show that tetrahydrofuran treatment causes the electronic energy state of the magnesium surface atoms to change, but the XRD studies show the crystal structure remains unchanged. Metallographic observation of the bulk hydrides of THF treated magnesium reveal they are poly-crystalline wi th the wide-spreading slip bands and twins within the crystals, indicating the phase transformation upon hydriding causes serious stress and distortion. It appears this microstructural deformation explains the much higher energy requirements (higher pressure and temperature) for magnesium hydrogenation than the simple lattice expansion that accompany hydrogen uptake for LaNi5 and FeTi.

• Research Organization: Savannah River Site (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC09-96SR18500
• OSTI ID: 824530
• Report Number(s): WSRC-MS-2003-00243
• Journal Information: Journal of Alloys and Compounds, Journal Name: Journal of Alloys and Compounds; ISSN 0925-8388; ISSN JALCEU
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
HYDROGEN
HYDROGEN STORAGE
MAGNESIUM
PHASE TRANSFORMATIONS
REACTION KINETICS
TETRAHYDROFURAN
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY