1 solid state chemical hydrides at pnnl 2010 nha conference and expo long beach ca. may 3-6, 2010 by...
TRANSCRIPT
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Solid State Chemical Hydrides at PNNL
2010 NHA Conference and Expo
Long Beach Ca. May 3-6, 2010
By
Jamie Holladay
Pacific Northwest National Laboratory
Outline
MotivationH2 storage for fuel cells
ApproachCombine theory, experimental and engineering
Mechanistic studies of H2 release (and uptake) from molecular complexes
ResultsMultiple chemistries for H2 storage were developed
• [NH4] + [BH4]¯ NH3BH3 + H2
• NH3BH3 NH2BH2 + H2
• [Li]+ [NH2BH3]¯ LiNHBH2 + H2
2
0
4
8
12
16
-200 -100 0 100 200 300 400
Temperature for observed H2 release (deg C)
Ob
serv
ed
H2 w
eig
ht
fra
cti
on
(%
)
LiBH4/CA
Ca(BH4)2
Mg(BH4)2
LiNH2/MgH2
MgH2
LiMn(BH4)3
NaAlH4
Li3AlH6/LiNH2
solid AB
AB/LiNH2
AlH3
liq. AB/cat.
1,6 naphthyridine
AB ionic liq.IRMOF-177
PANI
metal-doped CA
C aerogel
bridged cat./AX21
bridged cat./IRMOF-8
DOE system targets metal hydrides
adsorbents
chemical hydrides
carbide-derived C
M-B-N-H
AB/AT/PS
PANI
H2 Sorption Temperature (deg C)
0-100-200
Mg(BH4)2(NH3)2
Mg(BH4)2(AlH4)
Mg(BH4)2(NH3)2
Li3AlH6/Mg(NH2)2
3 G. Thomas, et al.,
Motivation: Amine Boranes If we understand mechanism, can we decrease the temperature for hydrogen release?
LiNH2BH3
NH4BH4
Height of bar corresponds to mass of element
4
Courtesy P Edwards Oxford
Element choices to store H limitedLi, Be, B, C, N, O, Na, Mg, Al, Si, P, S
NH4BH4 (24 wt% H2)NH3BH3 (19 wt% H2)LiNH2BH3 (12 wt % H2)
Gravimetric density challenges
NHxBHx H-storage (multi-step pathways – lots of interesting chemistry
T (˚C)NH4BH4 NH3BH3 + H2 <20 NH3BH3 (NH2BH2) + H2 <100NH2BH2 (NHBH) + H2 >1002(NH2BH2)n (NH2BH—NHBH2) n H2 <1502(NHBH) (NHB—NBH) + H2 >150NHBH BN + H2 >500
5
Two plus sequential steps > 13 % mass hydrogen material
If we can understand the details of the chemistry we can optimize the performance of a hydrogen store
Important Science Questions
NH3BH3 (NH2BH2)n + H2 + ? <100 ˚C
6
Is the mechanism intra or intermolecular?What is the activation barrier?Can we control the decomposition pathways?
How is H2 formed from solid AB?How is H2 formed from solid AB?
Need approaches to study solid state kinetics
∂+ ∂-Molecular Electrostatic Potential
hydridic B-H and protonic N-H hydrogens impart unique ability to store and release hydrogen
ApproachesScanning calorimetry combined with mass detection and gravimetric analysis
Thermodynamics of hydrogen lossKinetics and insight into mechanism of H-release
NMR and Raman spectroscopy Variable temperature for in-situ kinetic investigations Solid state to study phase transitions and molecular dynamics
Neutron spectroscopy QENS (for dynamics of H motion)NPDF & INS (structural properties)
7
Combination of experiment & theory to gain understanding of chemical & physical properties of AB
0 500 1000 1500 2000 2500 3000
Rela
tive
Hea
t R
ele
as
ed
(a
. u
.)
Time (min)
85 °C
80 °C
75 °C70 °C
Neat AB
8
Kinetics: isothermal DSC solid AB
• Rates increase with temperature
• Activated process
• Sigmoidal kinetics
• Induction period
• Thermodynamics
• ΔHrxn = -21±3 kJ/mol
NH3BH3(s) (NH2BH2)(s) + H2
Kinetic model for hydrogen release
Nucleation:Physical or Chemical Change
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Control chemistry if we know what is happening to ammonia borane during each phase of the reaction?
0.00
1.00
0 100 200 300 400
Sigmoidal kinetic behavior: Induction, Nucleation & Growth
Induction: How to decrease?
Growth: H2 formation
Ea ~ 150 kJ/mol
Ext
ent
of
reac
tio
n
Mechanism for Release from AB (induction, nucleation, growth)
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NH2
BH2
NH3
BH3
BH2
NH3
BH3
BH2
NH3
BH2
NH2
BH2NH3
NH2
BH4
BH4
NH3
NH3
H2
H
H di-H-bonddisruption
BH2
NH3H +
-DADB
D
DADB reacts with AB
NH3
BH2 BH4
NH3
+-
+ AB+-
+ AB
NH2
BH2
NH2
BH2
NH2
BH2
2 H2
CYCLICS
BH2
NH3
BH2
NH2
NH2
+-
BH2
NH3
BH
NH2
NH3
+-BH4
BH3BRANCHED
LINEAR
BH4
H2
H2
NH3
How can we ‘tweak’ or ‘meddle’ with the structure of AB, without sacrificing too much hydrogen, to improve the properties of AB for H2 storage?
Can we modify Ammonia Borane to:
• decrease exothermicity?
• increase the rate of hydrogen release?
• make it stable at 60°C?
• enhance the purity of H2 release?
• decrease the ‘foaming’ problem?
Tweaking Ammonia Borane: Additives on Release Kinetics
DADB – no induction period and a faster peak H2 release rate.
5% DADB & NH4Cl – similar kinetics, little induction period.
5% NaOH or NaBH4 – small effects.
Ammonia Borane at 80 ˚C
Diammoniate of Diborane
H2
Equ
ival
ents
Solid AB, 80 °C
Tweaking Ammonia Borane: Anti-Foaming AgentsSolid AB foamsExplored over 30 different additives
15wt% MC/AB
15wt% MC/AB heated to 180 oC
10wt% MC/AB heated to 180 oC
15wt% MC/AB (T2) heated to 180oC
Neat AB heated to 180oC
Best case:10-20 wt% of methyl cellulose (MC) prevents foaming with proper preparation. 100 mg AB >100 ml H2.
SEM images of MC/AB before
(above) and after (below) heating to
180 oC (loss of 2.5 eq of H2 (13 wt% H2)
13
0%
2%
4%
6%
8%
10%
12%
T=150°C T>150°C T > 150°C, AB:MCM
1:1
T > 150°C AB:BN 1:1
T>160°C, CoCl2
T> 160°C MAB
Wt.
% B
oraz
ine
Borazine Release at Atmospheric Pressure
Hydrogen Impurities
Solid ABAmmonia:100-250ppmBorazine: 0.8 wt% - 12 wt%
MABBorazine- 0 wt%Ammonia - 0.2 wt%
Remaining workHigh pressureNo sweepFilters
Catalysts, additives and temperature can control borazine.Ammonia is low
Medaling with ammonia borane
Medaling = Replacement of a hydrogen with a metal cation:
e.g., LiNH2BH3 (ca 12 wt% H2)
Can we modify thermodynamics (direct reversible?)
AB H2 loss is exothermic MH H2 loss is endothermic
Do we modify rate?break up di-hydrogen bonds
Do we maximize purity of H2
No NH3?No borazine?
MH-H2
Comparison H2 release AB vs LiAB
0 100 200 300 400 5000.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
gm
H2
/gm
of
ma
teri
al
Time (Sec)
LiAB
AB
LAB (at 130°C)
• 10 wt% H2
• no induction period• faster rate• more H2 (at 130°C)• no borazine• less exothermic
• 10X more NH3
Mechanism for H2 release from AB (induction, nucleation, growth)
Effect of other metals on MAB?What is the mechanism for H2 release from MAB?
0 3600 7200 10800 14400 18000 21600 252000
0.2
0.4
0.6
0.8
1
1.2
1.4
time (s)
eq
uiv
ale
nts
of
hyd
rog
en
What is effect of M (Li vs Na Vs K)?How do alkyl substituent's effect rates?
NaNH2BH
3 at 81 °C
KNH(Me)BH3 at 91 °C
LiNH2BH
3 at 81 °C
NaNH(Me)BH3 at 96 °C
KNH(tBu)BH3 at 131 °C
rate: Li < Na < K rate: tBu < Me < H
MAB release: metal mediated release of H2
i) bimolecular MH ‘elimination’ (formation of new B—N bond)
ii) 1,2 addition of [MH] with acidic NH (H2 release)
iii) unimolecular MH‘elimination’
iv) 1,4 addition of [MH] with acidic NH (H2 released)
Net Rxn 2 MNH2BH3 (M)NHBH(M)NHBH3 + 2 H2
HN
HH
M
NHBH BH3
NH2 NHBH
M
BH3
HH
M
BH2
NH2
H
NH
H
M
BH3
NH2 NHBH
BH3
BH2
NH2NHM
BH3
M
M
M
M
M
BH2
NH2
H
NH
H
M
BH3
M
BH2
NH2M
HBH3
NH2M4
5
6
7 HN
H3B
NHBHM
M+ H2
(1) (5t)
(5t)(6H2)
+ H2
(6H2) (7t)
(7t) (8)
Ammonia Borane
16 H2 wt% (material) usable gravimetric capacity (system target= 9 wt%)
120 gH2/L (material) usable volumetric capacity (system target= 80 gH2/L)
1.3 gH2/sec/kg AB release rate (system target = 0.022 gH2/sec/kg)Stability
50°C for over 90 days with no loss observedStable in air and water
Exothermic release 5 kcal/mol H2 (first equivalent)Release temperature – stepwise 90 – 160°CAdditives- improve performance
CoCl2 (IPHE collaboration)<1 wt% borazine60°C for release on-set – accelerated release
Anti-foaming additives demonstratedRegeneration
Off-board demonstrated
Metal Amidoborane Summary
Metal mediated releaseLi < Na < KtBu < Me < H
LiAB – 10 wt% H2
AdvantagesLower release temperature
Increased H2 purityLower exothermicity
Endothermic release demonstrated on low H2 capacity material
Is it possible to regenerate with H2 or an amine?Disadvantages
Lower H2 content Regeneration needs to be examined
Approach to Chemical Hydrogen Storage
DOE EERE Chemical Hydrogen Center of Excellence• Controlling release of hydrogen from AB
– Regeneration of AB off-board– Engineering, experiment and theory– Materials Discovery
DOE BES Hydrogen Fuel Initiative • Structure and dynamics (Neutron and NMR)
– Experimental and computational studies of di-hydrogen bonding interactions (H-/H+)
• Catalysis (XAFS and NMR)– In-situ spectroscopy and mechanistic investigations
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(amine boranes; T = 5 – 500K)
Abhi Karkamkar, Avery Luedtke, John Linehan, Wendy Shaw, Richard Zheng, Greg Schenter, Nancy Hess, Herman Cho, Tricia Smurthwaite, David Heldebrant, Shawn Kathmann, Don Camaioni, Michael Mock, Robert Potter, Dan Dubois, Jerry Birnbaum, Ashley Stowe, Doinita Neiner, Scott Smith, Bruce Kay, Mark Bowden, Roger Rousseau,
Jamie Holladay, Ewa Ronnebro, Yong Joon Choi
Summary Table H2 Release
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Summary of rates, enthalpies and purity of hydrogen. theoretical density (measured density). Bz = borazine. ? = not yet measured, will be determined in future work. All compositions tested are not shown. C= Continue, D = Discontinue for on or off
board transportation systems, still may be applicable for stationary or portable applications
compound gravimetric volumetric additive enthalpy peak rate temperature NH3 Bz notes
g H2/kg g H2/l kJ/mol g/s/kg C ppm wt%
NH3BH3 194 (160) 146 (120) none -23 1.3 160 100-250 4-12 foams
NH3BH3 " " none -23 0.93 145 100-250 2-4 foams
NH3BH3 " " none -23 0.43 130 100-250 2-4 foams
NH3BH3 + AF 155 (136) 117 (102) anti foaming -23 0.43 130 100-250 2-4 no foam
NH3BH3 155 117 CoCl2 ? ? 60 ? 0.8 no foam
AB:MCM " " scaffold (1:1) -1 (-22) 2.8 130 100-250 <1 no foam
AB:MCM " " scaffold (2:1) -10 ? 130 100-250 <1 no foam
AB:MCM " " scaffold (3:1) -12 1.9 130 100-250 <1 no foam
DADB 194 (160) ?? none -16 1.8 145 ? ? little foam
DADB " none -16 0.48 130 ? ? little foam
DADB " none -16 0.2 100 ? ? little foam
NH4BH4 240 130 none -63 ? 40 ? ? little foam
LiNH2BH3 109 52 none ? 1.76 130 200 0 no foam
LiNH2BH3 " " None ? 0.44 100 2000 0 no foam
LiNH2BH3 " " None -2 0.08 90 2000 0 no foam
LiNH2BH3 " " None 0.01 80 2000 0 no foam
NaNH2BH3 76 43 none ? 0.044 80 ? 0 no foam
NaMeNHBH3 30 ?? none ? 0.043 100 ? 0 no foam
KNH(Me)BH3 20 ? none ? ? 85 ? 0 no foam
KNH(tBu)BH3 15 ? none ? ? 130 ? 0 no foam
Backup
24
Recent results
• Roger Rousseau, Greg K. Schenter, John F. Fulton, John C. Linehan, Tom Autrey. Operando XAFS and AI MD to characterize Rhodium Clusters in the Catalytic Dehydrogenation of Aminoboranes. J. Am. Chem. Soc. 2009 ASAP.
• Annalisa Paolone, Oriele Palumbo, Pasquale Rispoli, Rosario Cantelli, Tom Autrey, Abhi Karkamkar. Absence of the structural phase transition in ammonia borane dispersed in mesoporous silica: evidence of novel thermodynamic properties. J. Phys Chem.C 2009, 113, 10319.
• Nancy J. Hess, Gregory K. Schenter, Michael R. Hartman, Luc L. Daemen, Thomas Proffen, Shawn M. Kathmann, Christopher J. Mundy, David J. Heldebrant, Ashley C. Stowe and Tom Autrey. Neutron Powder Diffraction and Molecular Simulation Study of the Structural Evolution of Ammonia Borane from 15 to 340 K. J. Phys Chem. A. 2009 DOI: 10.1021/jp900839c.
• Annalisa Paolone, Oriele Palumbo, Pasquale Rispoli, Rosario Cantelli, Tom Autrey. Hydrogen dynamics and characterization of the tetragonal-to-orthorhombic phase transformation in ammonia borane. J. Phys Chem. C. 2009, 113, 5872.
• Li-Qiong Wang, Abhi Karkamkar, Tom Autrey, Gregory J. Exarhos. Hyperpolarized 129Xe NMR Investigation of Ammonia Borane in Mesoporous Silica. J. Phys. Chem. C 2009, 113, 6485.
• Shawn M. Kathmann, Vencislav Parvanov, Gregory K. Schenter, Ashley C. Stowe, Luc L. Daemen, Monika Hartl, John Linehan, Nancy J. Hess, Abhi Karkamkar and Tom Autrey. Experimental and Computational Studies on Collective Hydrogen Dynamics in Ammonia Borane: Incoherent Inelastic Neutron Scattering. J. Chem Phys, 2009, 130 024507.
• Doinita Neiner, Abhijeet Karkamkar, John C. Linehan, Bruce Arey Tom Autrey and Susan M. Kauzlarich. Promotion of Hydrogen Release from Ammonia Borane with Mechanically Activated Hexagonal Boron Nitride. J. Phys Chem C. 2009, 113, 1098.
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Comparison of Energy Storage Approaches
Alternative Power H2FC high energy density compare to Li battery 10X
• remote power• telecommunications
• emergency power• first responders
• transportation power• vehicles
Tweaking Ammonia Borane- Impurity Measurement and Mitigation
Our approachAnalysis tools: NMR, FTIR, Mass spec etc. Develop Borazine formation mechanismTheory to understand barriers
Experimental set upTrap impurities
THF/GlymeNMR
FTIRTG-Mass spec/ RGA
Ammonia borane (NH3BH3)
Structure dominated by di-hydrogen bonding interactionsNH --- BH
Very dynamic (NH3 & BH3) rapidly rotating in place
Alkali Metal Amidoboranes (LiNH2BH3)
Structure dominated by interactions between N Li --- HB
Very little dynamical motion
Synthesis of Alkali Metal Amidoboranes
I) NH3BH
3 + Li*NH2 *NH3 + LiNH2BH
3
THF
M = Li; R = HM = Na; R = H, Me
M = K; R = MeM = Li; R = MeM = K; R = tBu
Synthesis adapted from that reported for Ca(NH2BH3)2 Burrell, A. K. et al. Angew. Chem. Int. Ed. 2007, 46, 8995.
II) NH2(R)BH
3 + MH H2 + MNH(R)BH
3
THF
Thermolysis of Solid LiNH2BH
3
No. Release of 1st equivalent of H2 is faster than release of 2nd equavalent of H2.
3070(30) s820(12) s
138(6) s
0 3600 7200 10800 14400 180000
0.2
0.4
0.6
0.8
1
1.2
1.4
81 °C86 °C91 °C
time (s)
equiv
ale
nts
of
hyd
rogen