Thesis - Oztek_Muzaffer_T_200508_MA

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0.4 0.3 Wt. % H desorbed 0.2 0.1 0.0 0 2000 4000 6000 8000 corrected time (s) Figure 16: Percent hydrogen desorbed for dehydriding of VTiNi. Even though the hydrogen uptake onset temperature of the VTiNi alloy was less than that of Mg 2 Ni, it had a lower hydrogen capacity at about 5 atm of initial H 2 pressure. Hydriding of the sample was complete in about 15 minutes, similar to Mg 2 Ni. 3.1.3. LaNi 5 The hydrogen uptake properties of LaNi 5 samples were determined under isothermal conditions at room temperature. This was possible because LaNi 5 forms a 44
solid solution of hydrogen rather than a covalent or metallic hydride as in the case of Mg 2 Ni, which required a considerable energy input to initiate the reaction with hydrogen. The LaNi 5 used in the first part of this study was obtained from Ergenics Inc. Unfortunately, Ergenics, Inc. stopped supplying the material and so the remainder of the work was done with alloy obtained from Alfa Aesar. The LaNi 5 obtained from Ergenics Inc. was shown to have a higher hydrogen capacity than the alloy obtained from Alfa Aesar but was otherwise a comparable material. Samples were activated for hydrogen uptake by ball milling and subsequent thermal treatment in a hydrogen atmosphere. The effects of ball to powder ratio and the type of mill on the activation of the alloy were studied. 3.1.3.1. Effect of Ball Milling Approximately 200 mg of LaNi 5 were directly transferred to the DSC sample boat without any treatment. The sample was subjected to thermal activation then was pressurized again with 5 atm H 2 and pressure was monitored at constant temperature. As no change in pressure, it is assumed that the sample did not react with hydrogen significantly. A second activation cycle was performed followed by the second constant temperature hydriding; however, the sample still did not react with hydrogen. In both of the constant temperature experiments, the non-milled sample took up only 0.05% H. The next LaNi 5 sample was prepared by ball milling in Spex8000 Mixer Mill for 10 minutes with a ball to powder ratio (BPR) of 10:1. Approximately 200 mg of sample 45
Page 1 and 2:
RECOVERY OF HYDROGEN AND HELIUM FRO
Page 3 and 4:
ABSTRACT Waste streams of hydrogen
Page 5 and 6:
I dedicate this work to my family m
Page 7 and 8: I also would like to cheer for my f
Page 9 and 10: 2.2.2.1. Hydriding and Dehydriding
Page 11 and 12: LIST OF FIGURES Figure 1. Pressure-
Page 13 and 14: Figure 34. Pressure profiles under
Page 15 and 16: 1. INTRODUCTION The focus of this s
Page 17 and 18: ecause of the difference in partial
Page 19 and 20: hydrides by dissolving large amount
Page 21 and 22: hydrogen storage alloy has a specif
Page 23 and 24: • Insensitivity to poisoning by i
Page 25 and 26: hydrogen capacity was not reproduci
Page 27 and 28: showed the lowest plateau pressure
Page 29 and 30: grain boundaries increases the tota
Page 31 and 32: These parameters are generally inte
Page 33 and 34: Figure 4. CaCu5-type P6/mmm structu
Page 35 and 36: In this study, the addition of Al t
Page 37 and 38: 2. EXPERIMENTAL 2.1.Chemicals and R
Page 39 and 40: Figure 5. The high energy Spex 8000
Page 41 and 42: 2.2.1.1. Hydriding and Dehydriding
Page 43 and 44: approximately 5 atm, and heating th
Page 45 and 46: determined by the start and end of
Page 47 and 48: 450 400 coating thickness (Å) 350
Page 49 and 50: 3. RESULTS AND DISCUSSIONS 3.1. Hyd
Page 51 and 52: DSC 111 heat flow/mW Exo 300 Figure
Page 53 and 54: The thermogram associated with the
Page 55 and 56: total time was broken into three 30
Page 57: The VTiNi sample was subjected to d
Page 61 and 62: DSC 111 Heat Flow/mW 180 Exo Figure
Page 63 and 64: 100 rpm setting, the milling vial w
Page 65 and 66: BPR, 400 rpm, 5 minutes) did not re
Page 67 and 68: Table 1: Effects of various milling
Page 69 and 70: Due to the fast kinetics observed a
Page 71 and 72: The mole % Al after milling was les
Page 73 and 74: Figure 24: Percent hydrogen capacit
Page 75 and 76: the start of the heating period, wh
Page 77 and 78: However, it was noted that the part
Page 79 and 80: percent hydrogen was decreased. The
Page 81 and 82: 3.2.2.4. AuPd and Pt Coating on LaN
Page 83 and 84: 1.0 0.8 (a) (b) Wt. % H absorbed 0.
Page 85 and 86: After dehydriding by the sample, th
Page 87 and 88: 19 18 P (atm) 17 16 15 14 0.74 %Al
Page 89 and 90: GC output, arbitrary units 0 5 10 1
Page 91 and 92: sample was LaNi 5 . This may indica
Page 93 and 94: 30 min. 15 min. Intensity (arb. uni
Page 95 and 96: After milling the percentages of Al
Page 97 and 98: 4. CONCLUSIONS This study has been
Page 99 and 100: 16. Van-Vucht, J.H.N., Kuijpers, F.
Page 101 and 102: 47. Suryanarayana, C., Progress in
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Thesis - Oztek_Muzaffer_T_200508_MA

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