MgH2 Tego Magnan powder

Fig. 2.27 XRD patterns of MgH2 (Tego Magnan) powders milled continuously for 100 h under the IMP68 mode in argon and subsequently desorbed directly after milling in a Sieverts-type apparatus at various temperatures...

Fig. 2.11 (a) PCT desorption curves at various temperatures for the activated commercial MgH2 Tego Magnan powder numbers indicate the average mid-plateau pressure, (b) The Van t Hoff plot for finding the enthalpy and entropy of decomposition, which is equal to -71 kJ/mol and 134 J/ mol K, respectively. Note excellent coefficient of fit R2 = 0.991 (p - pressure)... 

Fig. 1.29 Plot ln(-ln(l - a)) vs. ln(t) for dehydrogenation of MgH2 (Tego Magnan ) milled for 20 h and catalyzed by 5 wt% Ni (tests were done in temperature range 275-375°C using nonacti-vated powder)...

Figure 2.6a shows typical kinetic curves of first desorption carried out in a Sieverts-type apparatus at the initial hydrogen pressure of 0.1 MPa (atmospheric pressure of 1 bar) for the as-received, nonmilled, and nonactivated Tego Magnan powder. For each temperature, a fresh load of sample was desorbed. At each temperature in Fig. 2.6a, the desorption process is complete with 100% of MgH2 des-... 

Fig. 2.21 Particle size of Tego Magnan powder in the as-received state, after milling for 100 h under the high-energy impact mode (IMP68 with two magnets at six and eight o clock positions) and after three cycles desorption at 350°C under 0.1 MPa H2 pressure for 15 min annealing at 350°C under pre-vacuum for 15 min/absorption at 350°C under 3.2 MPa H2 pressure for 15 min. Grain size of 3-MgH2 is shown above each data point...

Fig. 2.32 DSC curves for the as-received MgH2 (Tego Magnan) and ball-milled MgH2 powders (IMP2 single magnet), (a) As-received commercial MgH2. Milled for (b) 15 min, (c) 1 h, (d) 10 h, (e) 25 h, (f) 50 h, (g) 75 h, and (h) 100 h in hydrogen (heating rate 4°C/min) [6]...

Fig. 2.33 DSC hydrogen desorption temperatures vs. particle size for as-received and ball-milled Tego Magnan powder, (a) Onset temperature (T ) and (b) low-temperature (LT) and high-temperature (HT) DSC peaks. Numbers beside data points indicate grain (crystallite) size of the P-MgH2 phase. Standard deviation bars for the particle size (ECD) are omitted for clarity [6]...

Fig. 2.3 (a) Scanning electron micrograph of the morphology of as-received Tego Magnan MgH2 powder and (b) powder particle size distribution (equivalent circle diameter, ECD)... 

Fig. 2.6 (a) Desorption kinetic curves at various temperatures under initial hydrogen pressure of 0.1 MPa of the as-received, nonactivated, commercial MgH2 powder Tego Magnan and (b) the Arrhenius plot of the desorption rate for the estimate of the apparent activation energy, EA, using kinetics data for four temperatures 350, 375, 400, and 420°C (f A -120 kJ/mol). Coefficient of fit R2 = 0.996... 

Fig. 2.48 DSC traces of Tego Magnan MgH2 powder doped with m- and n-Ni, and (a) mixed for 1 h without milling (no steel balls) and (b) mixed for 1 h with Tego Magnan MgH2 which was premilled for 20 h (heating rate 4°C/min argon flow rate 25 ml/min)...

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