Kevin Meaux
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Alternatives to fossil fuels to power transportation
are sought
To use hydrogen for fuel, a more effective way of
storing H2 is needed
High volumetric density, hydrogen mass %,
stability, and reversibility are desired
Liquid and gaseous H2 are not dense enough
Metal hydrides and similar compounds offer
potential solutions
description
Melting point
Nonhazardous stable white powder1
104 ⁰C (377 K)
Density
0.78 g/cm3
Mass % H
19.6%
Hydrogen Density
0.153 g H/cm3 H3N:BH3
1
For Comparison…
Mass % H of LiAlH4 10.6%
Mass % H of NaBH4 10.7%
Density of L H2
0.068 g/cm3
[1] Marder, T., Angewandte Chemie International
Edition, 2007, 46, 8116–8118.
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For effective use, more info is needed on the
dehydrogenation process of ammonia borane
(AB)
Important first steps involve developing a
working experimental setup to study this
change
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Using Transmittance
Fourier Transform Infrared
Spectroscopy
Characterizes a substance
by the vibration of its
chemical bonds
Infrared Spectroscopy Schematic
http://solidstate.physics.sunysb.edu/book/prob/node111.html
Original Experimental Setup
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KBr and NH3BH3 are mixed in a 25:1 ratio
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KBr alone and the KBr/AB mixture are pressed into a tungsten mesh in
different spots
Have varied the reference
salt, absolute amounts,
and ratios
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Sample is under rough vacuum
for analysis (~9E-2 torr)
Heated and then allowed to
cool under argon (~5 torr)
New spectra is taken at room
temperature and rough vacuum
copper leads
for resistive heating
sample
tungsten
mesh grid
reference
Image produced by Oleg Byl
10%
Our findings *
*This table compares
reference IR peaks for
ammonia borane with
data gathered for 300K
Literature
2
Assignment
3386
NH anti sym stretch
3309
3337
NH sym stretch
3259
3197
3224
3164
2427
???
???
10
B H stretch
2380
2415
B H stretch
2350
2340
BH stretch
1604
1656
1608
???
???
NH deformation
1558
1376
1591
1558
1343
???
???
NH deform
1301
2116
11
1252
1165
1186
NH rock
???
BH deform
1060
1060
B H deform
1052
B H deform
987
B N stretch
968
B N stretch
603
???
???
BH rock
[2] JJ. Smith, K. S. Seshadri, and David White:
J. Mol. Spec., 1973, 45, 327-337.
783
725
10
11
10
11
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The 1126,2225, and 2291 peaks shown
forming at 433 K correspond to KBH4 3
The 1959/2029 peaks formed at 913 K are
likely the formation of B11O2/B10O2 anions 4
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The other peaks observed at 433 K do not fit
with borazine, boron oxides, or boron nitride
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[3] K. B. Harvey and N. R. McQuaker: Canadian Journal of Chemistry, 1971,
49, 3272-3281.
[4] I.C. Hisatsune and Noelia Haddock Suarez: Inorganic
Chemistry, 1964, 3, 168-174.
Had problems
with KBr reactivity in
pellet preparation
 Instead it is prepared
on a KBr window
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Dissolved AB in THF
 Deposited solution on KBr disk
 Boiled off THF (67 C)
 Mounted disk onto
mesh
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Thermocouple
KBr Window
Thermal Dehydrogenation of NH3-BH3
515o C
455o C
375o C
275o C
150o C
120o C
1399
100o C
1563
670 877
1395
1663
1054
1129 1243
600
900
1200
1500
RT
2263
2328 2370
1800 2100 2400 2700
Wavenumber (cm-1)
3248 3284
3000
3300
3600
3900
2.9 mg NH3-BH3 dissolved in 0.7 mL THF and deposited on KBr disk. KBr disk is mounted on tungsten mesh, on which
thermocouple was spot-welded. Sample was heated under 0.1 torr pressure and spectra collected at room temperature.
*Evaporated THF solution on
KBr window
Pressed KBr Pellet
Literature
2
Assignment
3386 NH anti sym stretch
3284
3248
3309
3259
3197
2370
2328
2380
2350
2116
1663
1604
1563
1395
1558
1376
1243
1129
1054
1252
1165
1060
3337
3224
3164
2427
2415
2340
1656
1608
1591
1558
1343
1301
1186
1060
1052
987
968
783
725
670
603
NH sym stretch
???
???
10
B H stretch
11
B H stretch
BH stretch
???
???
NH deformation
???
???
NH deform
NH rock
???
BH deform
10
B H deform
11
B H deform
10
B N stretch
11
B N stretch
???
???
BH rock
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The new sample prep method shows more
clearly resolved peaks
The accuracy of temperatures needs to be
verified
The peaks are shifted somewhat from
literature values
The spectra demonstrates dehydrogenation
with heating
Neither the KBH4 nor BO2- peaks are seen
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AB can be useful as a hydrogen storage media
More work needs to be done in characterizing
its dehydrogenation
Current method yields noisy spectra but shows
potential
Will be dealing with the noise issues in the
near future
This work was supported by the National Science
Foundation under EEC-NSF Grant # 1062943
I would like to thank Dr. Trenary and Dr. Jash for their
guidance, as well as Dr. Takoudis and Dr. Jursich for
administrating the UIC REU program