jeff van humbeck macmillan group meeting april 14 storage for mobile applications jeff van humbeck...
TRANSCRIPT
Hydrogen Storage for Mobile Applications
Jeff Van Humbeck
MacMillan Group Meeting
April 14th, 2010
“The Stone Age did not end for lack of stone, and the Oil Age
will end long before the world runs out of oil.”
– Sheikh Zaki Yamani
(warning?) as Saudi OPEC Representative
Presentation Overview
! 5 dominant absorptive materials that have been investigated widely
! Not by any means comprehensive review of literature (1000s of papers since 2000)
CHEMIABSORPTIVE MATERIALS PHYSIABSORPTIVE MATERIALS
Conventional hydrides
Complex hydrides
Chemicals hydrides (ammonia borane)
Metal-organic frameworks (MOFs)
Nanostructured carbon (SWCNTs)
! For each material, attempt to highlight two main features:
What are the comparative advantages/disavantages of particular technologies?
What approach is current research taking to improve material characteristics?
Why Focus on Mobile Applications?
! Stationary power storage can use technology where the volume and mass of storage don't matter
DOE Hydrogen Storage Guidlines
! In 2003 Department of Energy sets hydrogen storage goals
Gravimetric Capacity Volumetric Capacity Operating Temperature/Pressure
2005
2010
2015
4.5 wt%
6.0 wt%
9.0 wt%
36 g/L
45 g/L
81 g/L
–30 to 50 ºC
<100 bar
http://www.eere.energy.gov/
! An onboard reversible system must have an endothermic hydrogen release
Determined
by !G
!S > 60 J/K (T!S strongly favors release) Must be favored by !H
Conventional Hydride Materials: Predictable Properties
! Crystalline starting material and products make calculating properties simple
Principi, G.; Agresti, F.; Maddalena, A.; Lo Russo, S. Energy 2009, 34, 2087.
Metal Alloy Conventional Hydride Gravimetric Uptake (wt%)
LaNi5
FeTi
Mg2Ni
ZrMn2
Mg
LaNi5H6
FeTiH2
Mg2NiH4
ZrMn2H2
MgH2
1.37
1.89
3.59
1.77
7.60
! Nearly demands the use of Mg (also, most cost effective)
! What is limiting application of MgH2 in hydrogen storage?
Conventional Hydride Materials: Uptake Kinetics
! Unmodified MgH2 requires high temperature for absorption/desorption
Engineering solutions
Ball milling: Reduce particle size, increase S.A.
Nanoscale scaffold synthesis:
HO OH H
O
H
Mg2
H2
Zhang, S., et. al. Nanotechnology, 2009, 20, 204027.
Porous
Polymer
Formation
Form
MgH2
Conventional Hydride Materials: Current State
! Most important features: Operating parameters, storage capacity, refilling kinetics
MgH2 + 5 wt% Ni MgH2 + 5 at% Mn MgH2 + 0.2 mol% Cr2O3 MgH2 + 0.5 wt% Nb2O5
Temp (ºC)
Kinetics (min)
Wt% H2
# cycles
230-370
90
6.00
800
200-300
8.3-13.3
6.00
N/A
300
2-6
6.70
N/A
300
1-1.5
7.00
N/A
Reiser, A.; Bogdanovic, B.; Schlichte, K. Int. J. Hydrogen Energy, 2000, 25, 425.
Liang, G.; Huot, J.; Boily, S.; Nestea, A. V.; Schulz, R. J. Alloys Compds. 1999, 292, 247.
Dehouche, Z.; Klassen, T.; Oelerich, W.; Goyette, J.; Bose, T. K.; Schulz, R. J. Alloys Compds. 2002, 347, 319.
Barkhordarian, G.; Klassten, T.; Bormann, R. J. Alloys Compds. 2004, 364, 242.
Reversible Hydrogen Uptake in Complex Metal Hydrides
! Similar strategy for improvement - transition metal dopant
! Different advantages/disadvantages compared to conventional hydrides
3NaAlH4 Na3AlH6 + 2Al + 3H2 Na3AlH6 3NaH + Al + 1.5H2
Dopants: Ti(OnBu)4, TiCl3, Zr(OiPr)4, Ti(s)
Advantages Disadvantages
Lower operating temperature (150-180) Kinetic charging/discharging (>60 min)
Stability (<17 cycles)
Sakintuna, B.; Lamari-Darkrim, F.; Hirscher, M. Int. J. Hydrogen Energy 2007, 32, 1121.
Chemiabsorptive Hydrogen Storage in Ammonia Borane
! B/N Coordination compounds fall into 3 main classes
! Inherently more hydrogen rich than simplest complex hydride (19.6wt%)
Hamilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279.
N-N and B-N
bonds
B-B and B-N
bonds
B-N bonds
only
H2N BH3
NH2H3B
B
B BH
H
H
H
H H
NH3
B N
HH
HH
HH
Likely to be explosive/shock-sensitive
B
H
H H
H
B
H
H NH3
NH3
Stephens, F. H.; Pons, V.; Baker, T. R. Dalton Trans. 2007, 2613.
! Isoelectronic with alkanes, but far more reactive (protic and hydridic bonds)
Solvolytic Hydrogen Release from Ammonia-Borane
! Solvolytic hydrogen release is more viable than for NaBH4
Hamilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279.
B N
H
H
H
H
H
H+4 ROH
–3 H2
[NH4][B(OR)4] Catalyzed by: acid, heat, precious metals, base metals
[NH4][B(OR)4]LiAlH4
NH4ClAl(OR3), NH3BH3, ROH, NH3, H2, LiCl
Ramachandran, P. V.; Gagare, P. D. Inorg. Chem. 2007, 46, 7810.
! Requires an efficient conversion of Al(OMe)3 to LiAlH4
Direct Dehydrogenation of Ammonia-Borane
! Formation of B–O bonds is energetic sink to be avoided
Hamilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279.
B N
H
H
H
H
H
H Catalyzed by: acid, base, precious metals, ligated base metals
! Mechanism for [Cp2Ti], (NHC)2Ni and (POCOP)IrH2 are representative
B N
H
H
H
H
–H2
Ti
Luo, Y.; Ohno, K. Organometallics 2007, 26, 3597.
Ni NPh
NPhNNPhN
NPh
Ph
Ph
COD
Keaton, R. J.; Blacquiere, J. M.; Baker, T. R. J. Am. Chem. Soc. 2007, 129, 1844.
O
O PtBu2
PtBu2
IrH
H
Denney, M. C.; Pons, V.; Hebden, T. J.; Heinekey, D. M.; Goldberg, K. I. J. Am. Chem. Soc. 2006, 128, 12048.
Initial N–Hcleavage
Initial B–Hcleavage
Concerted hydrogentransfer
Ti-Catalyzed Dehydrogenation of Ammonia-Borane
! Representative of initial N–H bond cleavage
Ti
Luo, Y.; Ohno, K. Organometallics 2007, 26, 3597.
TiN
H
BH3
Me
Me
TiH
B NH
H
Me
Me
HTiH
H
B N
H
H
H
Me
Me
H
B N
H
H Me
Me
H H
Initial
N–H
bond
cleavage
Catalyst generated
from TiCp2Cl2 and
nBuLi in situ
Iminoborane byproduct
slowly dimerizes under
reaction conditions
N
B N
B
Me
Me
Me
Me
H
H
H
H
Ni-Catalyzed Dehydrogenation of Ammonia-Borane
! Representative of initial B–H bond cleavage
Keaton, R. J.; Blacqueire, J. M.; Baker, T. R. J. Am. Chem. Soc. 2007, 129, 1844.
B N
H
H
H
H
H
H
B N
H
H Me
Me
H H
Initial
B–H
bond
cleavage
Nickel-NHC Catalyst
Iminoborane byproduct
form borazine and
higher polymers
Ni
Solv
N
N
N
N
N
N NPhPh
Ph
B
NB
N
BN
H
H
H
H
H
H
Ni
N
N
N
N
H BH2NH3
Ni
N
N
N
N
H BH2
NH3
Ni
N
N
N
N
H H
B N
H
H H
H
Ir-Catalyzed Dehydrogenation of Ammonia-Borane
! Representative of concerted hydrogen generation
Ankan, P.; Musgrave, C. B. Angew. Chem. Int. Ed. 2007, 46, 8153.
B N
H
H
H
H
H
H
B N
H
H H
H
H H
ConcertedN–H/B–Hbond
cleavage
Iridium-pincer complex
based on alkane
dehydrogenation catalyst
Iminoborane byproduct
slowly forms [H2NBH2]5
O
O PtBu2
Ir
PtBu2
H
H
O
O PtBu2
Ir
PtBu2
H
H
H
BH2NH3
O
O PtBu2
Ir
PtBu2
H
H
H
BH2
H NH2
O
O PtBu2
Ir
PtBu2
H
H
H
H
H2B
H2NBH2
H2N
B
H2N
BH2
NH2
BH2
H2N
Denney, M. C.; Pons, V.; Hebden, T. J.; Heinekey, D. M.; Goldberg, K. I. J. Am. Chem. Soc. 2006, 128, 12048.
Electronic Substitution of Ammonia-Borane
! Stabilizing dative bond creates endothermic reaction
Staubitz, A.; Besora, M.; Harvey, J. N.; Manners, I. Inorg. Chem. 2008, 47, 5910.
H3B NH3 H2B NH2 N
F3C
H B
F3C
H N
F3C
B
F3C
H
Electronic substitution does not stabilize true !-bond and dative "-bond as much as dative !-bond
! Clear tradeoff with gravimetric capacity (< 1wt%)
Improving Hydrogen Absorption Beyond Surface Area
! Optimal binding energy can be calculated from first principles (thermodynamic strategy)
Bhatia, S. K.; Myers, A. L. Langmuir 2006, 22, 1688.
!Hopt = T!Sopt + RT•ln P1P2
2P0
2
For a system operating at RT, between
1.5 and 30 bar: 15.1 kJ/mol
For a typical MOF with !Hadb = 6 kJ/mol
Operating temperature: 131K
For a system operating at RT, between
1.5 and 100 bar: 13.6 kJ/mol
! Is there any way to kinetically improve the hydrogen storage properties?
Hysteresis
(May be underestimated)
Thermodynamic Strategies to Increase Binding Enthalpy
! Increase interaction can be based on orbital or Coloumbic features
! These techniques have been applied (at least theoretically) to both MOFs and nanocarbons
WPiPr3OC
iPr3P CO
CO
HH
Kubas' Complex
Orbital overlap
M
H
H
Filled d/Empty !*
M
H
H
Empty p/Filled !
Up to 90 kJ/mol
Li+H
H
Metal ion
Coloumbic interaction
Up to ~24 kJ/mol
Li+ H H
"– "+
Dipole/Induced dipole
Kubas, G. J.; Ryan, R. R.; Swanson, B. I.; Vergamini, P. J.; Wasserman, H. J. J. Am. Chem. Soc. 1984, 106, 451.
Wu, C. H. J. Chem. Phys. 1979, 71, 783.
MOFs With Exposed Metal Sites
! Metal impregnation on organic linkers provides another avenue
O O
OO
Kaye, S. S.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 806.
MOF-5
Cr(CO)6, THF
nBuO2, 140 ºC
O O
OO
Cr
CO
CO
CO
h!
H2 (atm)
N2 (atm)
O O
OO
Cr
CO
H2
CO
O O
OO
Cr
CO
N2
CO