Preparation and Characterization of Iron-Oxide Catalysts
for Orthohydrogen-Parahydrogen Conversion
Erik Hemstad and Jacob Leachman
School of Mechanical and Materials Engineering
Counts
1600
Erik Hemstad
Jacob Leachman
(952) 994-4435
hemstad@stolaf.edu
hydrogen.wsu.edu
(509) 335-7711
jacob.leachman@wsu.edu
hydrogen.wsu.edu
ABSTRACT
EXJOT200-Petit
EXECH009-Petit
EXECH001-Petit
EXECH005-Petit
EXECH008-Petit
900
400
100
0
2
4
6
The objectives of this project are the synthesis and characterization of paramagnetic orthohydrogen / parahydrogen conversion
catalysts of mesoporous microstructure (2 – 50nm diameter). Soft templated γ-Fe2O3 catalysts were prepared according to Mitra
et al.. The influences of certain parameters on the materials were studied: the affect of aging and the method of recovering the
solids after precipitation. Template removal was carried out by solvent extraction. The solids were characterized by: X-ray
diffraction (XRD); Tunneling Electron Microscopy (TEM); Scanning Electron Microscopy (SEM); and N2 adsorption. Some
preliminary results coincide with Mitra et al., however further characterization is needed. Work has begun on a liquid hydrogen
reaction chamber for verification of catalyst activity. This research is the first step towards publishable results of orthohydrogen
/ parahydrogen conversion rates in the HYdrogen Properties for Energy Research (HYPER) laboratory at WSU.
Position [°2Theta]
MOTIVATION: UAV
FIGURE 1. Small Angle XRD
results (shown clockwise); Mitra
et al. [as-synthesized (c) and
template extracted (d)], template
extracted analyzed by Dr. Daou’s
lab, and as-synthesized analyzed
by Dr. Daou’s lab.
Counts
1600
JOT200-Petit
ECH009-Petit
ECH001-Petit
ECH005-Petit
ECH008-Petit
900
400
100
0
2
4
6
Position [°2Theta]
ORTHO / PARA CONVERSION
Liquid hydrogen fuel leads the aerospace industry, having 2.8
times more energy per mass than conventional hydrocarbon
alternatives. Current liquid hydrogen fueling systems must
be pressurized via an external source and are thus burdened
by heavy helium tanks or by power mongering heaters.
However, a new class of paramagnetic catalysts presents the
opportunity to use the hydrogen molecule itself as the heat
source, superseding conventional pressurization systems.
This new class of catalytic pressurization system holds the
potential for a much lighter system chassis, reduced power
consumption, and consequently a larger payload in
applications such as Unmanned Aerial Vehicles (UAV).
At room temperature hydrogen consists of 75% orthohyrogen
and 25% parahydrogen (Schmauch and Singleton 1964). These
terms refer to the nuclear spin orientation of the molecules,
ortho referring to parallel spins, and para referring to antiparallel spins. At cold enough temperatures, ortho / para
conversion is naturally prohibited because of rotational quantum
numbers, para: even, ortho: odd. Therefore, to cause this
conversion at low temperatures an external magnetic field must
be applied, reversing the nuclear magnetic field and thus the
nuclei spin. This effect can occur when placed in contact with a
X66000
material with high paramagnetic susceptibility (Schmauch and
Singleton 1964).
FIGURE 4. Microscopy images (shown clockwise); TEM Mitra et al.
template extracted, TEM (X115000) template extracted analyzed by
A template solution (1.44g sodium dodecyl sulfate (SDS) in 20 ml distilled water) was prepared and .54g benzyl alcohol (BA) Dr. Daou’s lab, TEM (X66000) template extracted, and SEM
was added drop wise to it. An ice-cold ferric solution (3.24g anhydrous ferric chloride in 5 ml distilled water) was then added (X80000) template extracted.
PREPARATION PROCEDURE
to the template solution while stirring. The pH was changed to a set level (5.5 by default) by adding tetraethylammonium
hydroxide (40% aqueous Aldrich) drop wise. The solution was then put in an ice bath and stirred vigorously for 2 hours. Aging
occurred at 277˚ K for a set duration (72 hours by default). The precipitate was filtered out using a Buchner after several rinses
with distilled water. The sample was then dried either by sublimation (cooled to 77˚ K and put under vacuum for 3 hours) or
evaporation (heated to 333˚ K for 24 hours). The sample was then suspended and vigorously stirred (3 hours) in a solution of
1g ammonium acetate (50%) and 49g ethanol. The precipitate was filtered out using a Buchner after several rinses with ethanol.
The template extraction process was repeated three times to ensure complete removal.
Sample Name
JOT200
ECH001
ECH003
ECH004
ECH005
ECH006
ECH007
ECH008
ECH009
ECH010
Counts
JOT200
ECH009
ECH001
ECH005
ECH008
400
225
100
10
20
30
40
50
60
70
80
Position [°2Theta]
FIGURE 2. Wide Angle XRD results (shown clockwise); Mitra et al.
[as-synthesized (c) and template extracted (d)], template extracted
analyzed by Dr. Daou’s lab, as-synthesized analyzed by Dr. Daou’s
lab, and as-synthesized.
Start Date
06.06.11
06.07.11
06.21.11
06.28.11
06.28.11
06.28.11
06.28.11
06.29.11
06.29.11
06.29.11
Mass (g)
2.12
2.62
2.81
2.99
2.96
2.1
1.59
3.23
3.11
3.11
Extracted Mass (g)
0.51
0.38
0.28
0.27
0.35
0.44
0.42
0.46
0.52
0.5
pH
5.5
5.5
5.5
5.6
5.8
6.5
10.2
5.5
5.5
5.5
277˚ K Age Time (hours)
72
72
72
72
72
72
72
24
48
72
Drying Temp (˚K)
333
333
333
77
77
77
77
77
77
77
Drying Time (hours)
24
24
72
3
3
3
3
3
3
3
FIGURE 3. N2 Adsorption results
(shown clockwise); Mitra et al.
TABLE 2. Sample preparation information.
template extracted, template
extracted analyzed by Dr. Daou’s
RESULTS OF CHARACTERIZATION
The small angle XRD data (FIGURE 1) shows a local maximum intensity (potentially indicating mesostructure formation) in the lab,
and
microporous
/
following as-synthesized samples: Mitra et al., JOT200, and ECH005, around 2˚, 1.5˚, and 1.25˚ (2θ) respectively. These local mesoporous reference chart.
maxima are not observed in ECH008 or ECH009, suggesting a dependence on the aging period. They also reduce in intensity
(Mitra et al.) or disappear entirely (JOT200 and ECH005) as the template is removed. The wide-angle XRD data (FIGURE 2)
show common peaks at 35˚ and 60˚ (2θ) indicating the phase presence of α-Fe2O3, ɣ -Fe2O3, and ɣ -FeOOH. An as-synthesized
peak around 20˚ (2θ) is characteristic of the SDS templating and disappears completely after template extraction. Lower intensity
displayed by ECH008 while not found in ECH009, also suggest the importance of age duration. The N2 adsorption data (FIGURE
3) show similar (and characteristically mesoporous) trends between Mitra et al., ECH008, and ECH009, suggesting that age
duration may also affect N2 adsorption. Increases in BET surface area (TABLE 2) from ECH008 to ECH009 to Mitra et al.
support the argument for age duration dependence. Samples ECH001 and ECH004 appear to have undergone sintering as a result
of excessive temperature while degassing. The TEM images (FIGURE 4) appear to agree, allowing for quantitative measurement
of pore size and d-spacing. Mitra et al. suggests a visible pore size of 2.5-2.8 nm with a d-spacing of 4.4 nm, which agrees with
the pore size of 2.1 -2.5 nm calculated through N2 adsorption. The SEM image allows for qualitative observations of the high
surface area of these catalysts.
FUTURE WORK
The HYPER lab will finish the material characterization, by securing magnetic analysis using a Superconducting QUantum
Interference Device (SQUID). Catalyst experimentation and optimization will continue with aims towards a patent. Once a
suitable catalyst is synthesized, work will begin on designing and building a test chamber, to test catalytic activity by measuring
hydrogen vapor production. Lastly, work will begin on designing a catalyst delivery system based on controlling the amount of
catalytic surface area contact with the hydrogen or by varying the magnetization via an applied magnetic field.
ACKNOWLEDGEMENTS
FIGURE 3. ECH010 spill during template
extraction,
exhibiting
strong
magnetic
characteristics.
This work was supported by the National Science Foundation’s REU program under grant number DMR 1062898 and the School of Mechanical and Materials Engineering at
Washington State University. We thank Joumana Toufaily for her comments and suggestions, Mike Rowe; Su Ha; Oscar Marin Flores; and Professor J. Daou from the Institute
of Materials of Mulhous, University of Haute Alsace, France; for providing technical assistance during the preparation of this paper.
References:
1.
2.
3.
A. Mitra, C. Vazquez-Vazquez, M. A. Lopez-Quintela, B. K. Paul, A. Bhaumik, Microporous Mesoporous Mater. 131 (2010) 373.
M. G. Millis, R. T. Tornabene, J. M. Jurns, M. D. Guynn, T. M. Tomsik , T. J. Van Overbeke, NASA/TM-2009-215521.
G. E. Schmauch, A. H. Singleton, Indust. And Engin. Chem. 56.5 (1964) 20.
School of Mechanical and Materials Engineering
Samples
Degas
Degas Surface
(Extracted) Temperature Duration BET
(˚C)
(Hours) (M2.g-1)
ECH 001
350
10
40
ECH 005
350
10
44.72
ECH 008
150
3
208.52
ECH 009
150
3
261.75
ECH 010
150
1
174.8
Mitra et al.
150
3
306
Pore
size
(nm)
n/a
n/a
n/a
n/a
n/a
2.1 2.5
TABLE 2. N2 Adsorption
sample
preparation
information, BET surface
area, pore size