Hydrogen storage in solids
Research phase
•Physical storage (adsorption - low T):
• Carbon Based materials
Zeolites
• Self-assembled nano composites/aerogels (foams)
• Zeolites (crystalline nano porous materials)
• Metal Organic Framework (MOF)
• Glass micro spheres
• Boron nitride nano tubes
• Hydrided amorphous carbon
MOF-5
IRMOF-6
IRMOF-8
Source: SCIENCE 300 (16 MAY 2003), pp. 1127,
• Hydrogen in hydrates & clathrates
The Fuel Cell Review 1:1 (2004), pp. 17-23
47
Hydrogen storage in solids
Research phase
•Chemical storage:
• Bulk crystalline /amorphous materials (multicomponent alloys)
• Chemical storage media (methanol, ammonia, etc)
• Reversible hydrogenation of organic liquids (CxHyOz):
Isopropanol + heat ↔ acetone + Hydrogen
<<100% selective
catalytic reactions
48
4
8
Why metal hydrides for storage?
• Safe (limited amount of free H2)
• High vol. capacity
• Relative low hydrogen pressure and ambient temperature
• Large quantities available
• Promising for mobile applications
49
Metal hydrides for hydrogen storage
Chemical metal hydrides
•
•
A(H)x + H2O → AOH + H2 (A, B, metals)
2 – 8 wt.% hydrogen
Conventional inter-metallic metal hydrides
•
AxBy + H2 → AxByHz
•
1 – 4 wt.% hydrogen
•
(4d metals)
MRS BULLETIN/SEPTEMBER 2002 699-703
50
Metal hydrides for hydrogen storage
Magnesium based metal hydrides
•
•
•
•
Mg + H2 → MgH2
Up to 7.6 wt.% hydrogen
Doping, catalysts, preparation methods
Tdec = 300°C
MgH2
Complex light weight metal hydrides
LiBH4
•
M(AlH4) alanates, 7- 10 wt.%, Tdec = 100-200°C
•
M(BH4) borohydrides, 10- 18.5 wt.%, Tdec = 125-350°C
51
Conventional intermetallic metal hydrides
Low hydrogen absorption/desorption temperature/pressure
More cycles possible
High volumetric storage capacity
Good hydrogenation kinetics
Low gravimetric storage capacity, 1 – 4 wt.% hydrogen
Not suited for mobile applications!
52
Magnesium based metal hydrides
Up to 7.6 wt.% hydrogen (MgH2)
More cycles possible
Slow absorption/desorption kinetics
Unfavourable thermodynamics for mobile applications:
(Tdesorption ~ 300˚C)
A lot of research performed: No reversible Mg - based
hydrides with low ∆H and high wt.%!
53
Alanates
Effective up to 5.6 wt.% hydrogen release
Desorption temperature (< 150oC)
Desorption is a 2 step process, more cycles possible?
(more reactions possible – cyclability?)
3NaAlH4 (7.4 wt. %) ↔ Na3AlH6 + 2Al + 3H2 3.7 wt. % H2 release
Na3AlH6 (5.9 wt. %) ↔ 3NaH + Al + 3/2H2
1.9 wt. % H2 release
Absorption involves a low T solid state reaction
Kinetics problems - catalyst (TiO2) is required
54
Borohydrides
High gravimetric storage capacity up to 18.5 wt.%
Desorption is a 2 step process
Absorption involves a low T solid state reaction
High desorption temperature (>250oC)
Cyclability is a problem (SiO2 catalyst required)
Expensive hydrides (preparation/energy consumption)
Source: J-Ph. Soulié, G. Renaudin, R. Cerny, K. Yvon, J. Alloys and Comp. 346 (2002), pp. 200-205
A. Züttel et al., Journal of Alloys and Compounds 356–357 (2003), pp. 515–520
55
Ceramics: Nitride
Amides (LiNH2)
From Lithium amide (LiNH2) to Lithium imide (Li2NH)
reaction
Li3N + 2H2 ↔ LiNH2 (8.8 wt.%) + 2LiH
LiNH2 + 2LiH ↔ Li2NH + LiH + H2
10.3 wt.% H2, -44.5 kJ/mol
Source: Chen P; Xiong Z R; Luo J; Lin J; Tan K L,
Nature 420 (21 November 2002), pp. 302-304
56
Amides (LiNiH2)
High gravimetric capacity (10.3 wt.%)
Multiple reaction processes
High desorption temperature
Cyclability?
Early experimental phase
LiNH2 + 2 LiH
Li3N
Source: Nature 420 (21 November 2002), pp. 302-304
57
Comparison hydrogen storage methods
Ref: A. Züttel, “Materials for hydrogen storage”, materials today, September (2003), pp. 18-27
58
Comparison hydrogen storage methods
25
125 C
Be(BH 4)2
Gravimetric capacity (wt. %)
20
LiBH 4
Target
Mg(BH 4)2
15
Ca(BH4)2
LiAlH 4
10
Mg(AlH 4)
6 wt.% NaAlH4
5
NaBH4
LiNH2+2LIH
Ca(AlH4)
KBH 4
LiH
MgH2 5 bar
Mg2FeH6 1 bar
LaNi5H6 2 bar
Mg2NiH4 4 bar
0
0
50
100
150
200
250
Desorption temperature (C)
59
300
350
400
Interesting metal hydride options
www.hydpark.ca.sandia.gov contains data on 2000 hydrides,
none of those meeting the targets for automotive application!
Reactive metal hydrides:
• Combinations of MgH2 + different hydride
- (lowering the ∆H by endothermic formation)
2NaH + MgB2 + 4H2 ↔ 2NaBH4 + MgH2
CaH2 + MgB2 + 4H2 ↔ Ca(BH4)2 + MgH2
2LiH + MgB2 + 4H2 ↔ 2LiBH4 + MgH2
∆H = -64 kJ/mol H2 7.8 wt.%
∆H = -30 kJ/mol H2 8.3 wt.%
∆H = -46 kJ/mol H2 11.5 wt.%
G. Barkhordarian et al.: GKSS patent application 2004,
G. Barkhordarian et al., J. Alloys Compd. (2006), doi:10.1016/j.jallcom.2006.09.048
J.J. Vajo et al.: patent application 2004, J. Phys. Chem. B 109 (2005) 3719-3722
60
Reactive metal hydrides
G. Barkhordarian et al.: GKSS patent application 2004,
G. Barkhordarian et al., J. Alloys Compd. (2006), doi:10.1016/j.jallcom.2006.09.048
J.J. Vajo et al.: patent application 2004, J. Phys. Chem. B 109 (2005) 3719-3722
61
Reactive metal hydrides
High gravimetric storage capacity ca. ~10 wt.%
Low desorption temperature (<125oC)
Desorption is a multistep process
Absorption involves a low T solid state reaction
Cyclability?
Still a lot of R&D necessary
62
Solution:
High throughput screening of metal hydrides
using…..
Hydrogenography
Source: Adv. Mater. 2007, 19, 2813-2817
Scripta Materialia 56 (2007) 853-858
63
Stability of hydrides: Van’t Hoff plot
Source: www.nat.vu.nl/CondMat/griessen
64
Wrapping up:
• CO2 free hydrogen can be made from fossil fuels if centralised
• Pressurised gas @ 700 bar is a viable/already available option for
storage
• Light metal hydrides are not yet suitable for mobile applications and
a lot of R&D is still necessary (not all options investigated)
• Stationary applications are very well possible (heavy)
• The existing storage options still do not comply to all long term
goals:
• Realistic goals as to temperature, driving range, size??
• Car concept??
65
The advantage of metal hydride storage ??
A. Zuttel
66
Gasoline
Mg2FeH6
LaNi5H6
H2 (liquid)
H2 (350 bar)
32 MJ/ltr
18 MJ/ltr
10 MJ/ltr
8 MJ/ltr
2.4 MJ/ltr
Synthetic fuels??
• Reverse Water Gas Shift
CO2 + H2 ↔ H2O + CO
• From waste CO2 and durable H2 we obtain durable
syngas, ready for Fischer-Tropsch based synthetic
fuels.
67
Thinking about the future of energy…..
Sponsors:
Co-workers:
The group Hydrogen Production and Carbon
Capture at ECN
The group Membrane Separations at ECN
The group Materials for Energy Conversion and
Storage at TU Delft
The group 3ME at TU Delft
68