Paper
Effect of TiC and Mo2C on Hydrogen Desorption of Mechanically Milled MgH2
- Authors:
- Congxiao Shang; Mi Tian
- Abstract
- Titanium carbide (TiC) and molybdenum carbide (Mo2C) particles were selected to modify the hydrogen storage properties of magnesium hydride (MgH2). (MgH2+ 2 mol% TiC) and (MgH2+2 mol% Mo2C) mixtures were prepared using both cryogenic milling and high-energy ball milling. The morphology and crystallite structure of the mixtures were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The milled (MgH2+TiC) and (MgH2+Mo2C) composites consisted of γ-MgH2 and β-MgH2. TiC nanoparticles with the size of 10~20 nm after milling were deposited onto the surface or into the grain boundary of MgH2. Mo2C were uniformly distributed on the surface of MgH2 particles. Thermogravimetry and derivative thermogravimetric analyses showed that ~6.5 wt. % hydrogen was desorbed from (MgH2+TiC) mixture in the temperature range from 190 to 400 °C at a heating rate of 10 °C/min under He flow. The on-set and peak temperatures were 190 and 280 °C, respectively, for (MgH2+TiC) ball-milled up to 60 hrs after 8 hrs cryomilling. However, (MgH2+Mo2C) shows much higher desorption temperature of 300 °C (on-set) and 358 °C (peak), respectively, compared with those recorded for (MgH2+TiC). The hydrogen desorption activation energy of the milled (MgH2+TiC) mixture, 104 kJ/mol, was also substantially reduced, compared with that of the (MgH2+ Mo2C) mixture, 167 kJ/mol. The addition of TiC nanoparticles has greater effect on reduction of hydrogen desorption temperatures and acceleration of desorption kinetics.
- Keywords
- Hydrogen Storage; MgH2; TiC; Mo2C; Nanoparticles; Mechanical Milling; Cryogenic Milling
- StartPage
- 54
- EndPage
- 59
- Doi