Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling
نویسندگان
چکیده
The effect of extended H2 sorption cycles on the structure and on the hydrogen storage performances of MgH2 powders with 5 wt% of Fe particle catalyst is reported. MgH2 powders with and without Fe have been ball milled under Argon, the doped MgH2 nanocomposite has been cycled under hydrogen pressure up to a maximum of 47 desorption and absorption cycles at 300 °C. After acceleration during the first 10 cycles, the kinetics behavior of doped MgH2 is constant after extended cycling, in terms of maximum storage capacity and rate of sorption. The major effect of cycling on particle morphology is the progressive extraction of Mg from the MgO shell surrounding the powder particles. The Mg extraction from the MgO shell leaves the catalyst particles inside the hydride particles. Many empty MgO shells are observed in the pure ball milled MgH2 upon cycling at higher temperature, suggesting that this enhancement of the extraction efficiency is related to the higher operating temperature which favors Mg diffusivity with respect to the H ion one.
منابع مشابه
H2 Desorption from MgH2 Surfaces with Steps and Catalyst-Dopants
Light-metal hydrides, like MgH2, remain under scrutiny as prototypes for reversible H-storage materials. For MgH2, we assess hydrogen desorption/adsorption properties (enthalpy and kinetic barriers) for stepped, catalyst-doped surfaces occurring, e.g., from ball-milling in real samples. Employing density functional theory and simulated annealing in a slab model, we studied initial H2 desorption...
متن کاملImproved hydrogen storage properties of MgH2 doped with chlorides of transition metals Hf and Fe
The effects of HfCl4 and FeCl3 addition on the de/rehydrogenation properties of MgH2 were investigated. Both HfCl4 and FeCl3-doped MgH2 samples started to released hydrogen at about 270 °C, a decreased of about 70 °C and about 140 °C compared to as-milled and as-received MgH2, respectively. In terms of the desorption kinetics, the HfCl4-doped MgH2 sample showed significant improvement, with 6.0...
متن کاملMicrostructural Evolution of Roll Bonded Al-Clad Stainless Steel Sheets at Elevated Temperatures
The cold roll bonding of Al on AISI 304L stainless steel was carried out to fabricate the Al/304L/Al clad sheet composites. The maximum bond strength of 20 N/mm was acquired just by 38% reduction, for which the tearing of the aluminum sheet occurred during the peeling test. The microstructural evolution during subsequent postannealing heat treatment was systematically studied based on the impur...
متن کاملThe effect of nano transition metals on microstructure and phase evolution of low carbon MgO-C refractories
In the present study, the effect of Iron Nitrate as catalytic precursor to in situ formation of nano-Fe particles in phenolic resin and microstructural evolution of MgO-C refractories has been investigated. Therefore, various samples according to matrix section formulation of low carbon MgO-C refractories (LCMCR’s) with 0 and 6 wt% (Fe/Phenolic resin) were prepared and phase and microstructure ...
متن کاملChemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage† †Electronic supplementary information (ESI) available: Experimental and computational details, free energy plots for the NH3 evolution and N2 reduction with Co3N/Co, Fe4N/Fe, Mn5N2/Mn4N, Mo2N/Mo, CrN/Cr2N, TaN/Ta2N, NbN/Nb2N, Li3N/LiH, Ba3N2/BaH2, Sr3N2/SrH2, and Ca3N2/CaH2, surface oxidation energetics, ΔGvac[NH*x, yH*] based on gas phase H2 as hydrogen source, NH3 evolution with Fe-doped Mn4N, NH3 evolution with Mn6N2.58, Ca3N2 and Sr2N after correcting for partial nitride hydrolysis, NH3 yield from Ca3N2vs. time and H2 gas flow rate. See DOI: 10.1039/c5sc00789e
متن کامل