This study investigated the effect of sodium hydroxide (NaOH) concentration on the rate of hydrogen gas production through aluminum hydrolysis. Testing was conducted with NaOH concentrations of 0.1M, 0.5M, 1M, and 2M. The results showed that higher NaOH concentrations produced hydrogen gas at faster rates, with the fastest rate seen at a concentration of 2M. Specifically, the 2M concentration produced hydrogen at a rate of 5.4 mL/min, around 400% faster than the 1M concentration rate of 1.3 mL/min. The author attributes the significant increase in rate between concentrations to a build-up of aluminum oxide byproduct that may have inhibited the reaction at lower concentrations tested

1. AIES Independent Study
June 4, 2015
Hydrolysis Kinetics and Efficiency for Hydrogen Production On-board Vehicles
Marissa Walter
Advisor: Tareq Abu-Hamed
Abstract:
Hydrolysis, or ‘water splitting’, emits no pollution, and recent studies suggest
that solar energy could be used to recycle the metal oxidized in the process, which
could close the loop of this process and make a storable and transportable, in the
form of Hydrogen (H) fuel form of solar energy, that is more competitive with fossil
fuels. This study investigated efficient hydrogen production, for use on-board
vehicles, by measuring the effects of the catalyst, Sodium Hydroxide (NaOH),
concentration on the rate of production of hydrogen gas. The time required to
produce 50mL of H gas was recorded for exactly calculated amounts of Water,
Aluminum foil, and NaOH. A positive correlation was seen between NaOH
concentration and H production rate, and a significantly fastest rate for the
concentration of 2.0M.
Introduction:
In recent decades, we have come to understand the serious consequences of
fossil fuels, but energy is still critical for today’s higher standard of life. Global
energy demand is currently 16.9TW and is expected to continue to grow with
population. Oil resources and reserves are expected to last for 40 to 150 years (Katz,
2015), but to keep using oil as usual will increase emissions of CO2, methane and
nitrous oxide - emissions, which are already unprecedented,1 and have deemed
extremely likely to be a major cause of climate change (IPCC Fifth Assessment
Synthesis Report, 2014). Thus, finding cleaner alternative energy sources is crucial.
Of the renewable energy sources, solar power may be the most practical for meeting
the global energy demand. It is estimated that enough energy from the sun hits the
earth in an hour to meet the world’s energy use for a year (Katz, 2015). 2
For vehicles, alone, the world uses ~22,596,500 barrels of gasoline per day
(U.S. Energy Information Administration, 2012). The problems with this usage
include pollution (esp. carbon monoxide, non- methane hydrocarbon, oxides of
nitrogen, volatile organic compounds, and heavy metals), 11,830.5 million metric
tons of CO2 emissions per year (U.S. Energy Information Administration, 2012),
finite and dwindling fossil fuel resources, rising costs, and dependence on imported
1 “[] has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are
unprecedented in at least the last 800,000 years.” – IPCC Fifth Assessment Synthesis Report, 2014
2 This theoretical amount is 350,000TW; the practical estimation is closer to 600TW (though estimates vary
by 100-2500TW). Since current conversion efficiency is 10%, the estimates for onshore electricity
production potential is ~60TW (Katz, 2015).

2. AIES Independent Study
June 4, 2015
oil. The impacts of transportation will only increase with population growth. The
world’s 600 million light-duty vehicles may very well double by 2020 (MacLean, H.
L., & Lave, L. B., 2003). 95% of these vehicles are dependent on oil (Mayyas et al.,
2012), but with new technologies, such as hydrogen, this number will be able to
decrease.
There are, at present, three main ways of harvesting solar energy: solar
thermal, photovoltaic, and fuels. There are tradeoffs for each approach; price,
efficiency, storage, and distribution are all major challenges for the adoption of solar
power. Fuels may offer a cheaper alternative to the more efficient photovoltaic
(Katz, 2015).
The process of hydrolysis, or ‘water splitting’, can make solar energy storable
and transportable, in the form of Hydrogen (H) fuel (see Equation 1 and Figure 1),
produces no CO2 (or other pollutants) in the production of H or the burning of H
(Katz, 2015; Abu-Hamed, Karni, & Epstein, 2007), and therefore has the potential to
make renewable energy more easily adopted as a substitute for fossil fuels (Katz,
2015; Abu-Hamed, Karni, & Epstein, 2007).
Metal + H2O  Metal Oxide + H2 (1)
Figure 1: Hydrolysis reaction model
The principle chemical reaction in this experiment is:
2 Al + 3 H2O  Al2O3 + 3 H2 (1)
(with NaOH as a catalyst)
According to recent studies, metals such as boron, zinc and aluminum can be
used in hydrolysis of water. These studies also suggest that solar energy could be
used to reverse the oxidation of metal, a by-product of the hydrolysis (Irina
Vishnevetsky, 2008), recycling the metal for reuse in hydrogen production.

3. AIES Independent Study
June 4, 2015
Furthermore, aluminum in the process can come from waste aluminum, such as
aluminum cans (Martınez et al., 2005).
However, as of 2005, no hydrogen storage technologies could compete with
conventional internal combustion engines (ICE) in terms of volume constraints (and
by extension vehicle ranges), and cost (Burke & Gardiner, 2005). Hydrogen has also
been viewed critically because of its explosive nature, but on-board hydrogen
production in vehicles could substitute hydrogen with a benign metal, making
storage and transportation safer and reduce volume constraints (Abu-Hamed et al.,
2007).
The aim of this research is to better understand the hydrolysis kinetics
(speed) and efficiency of hydrogen production, as well as to investigate possible
improvements in on-board hydrogen fuel production in vehicles. Specifically, this
study will look at the effects of the catalyst, Sodium Hydroxide (NaOH),
concentration on the rate of production of small amounts of hydrogen gas, through
metal hydrolysis (see Equation 1). Finding the NaOH concentration that produces
the most efficient reaction could solve some of the problems on-board H production
faces (such as volume and weight constraints).
This type of research is important to the global transition from fossil fuels to
solar power. Better understanding of the hydrolysis kinetics (speed) and best
practices for efficient Hydrogen production, could increase the development on-
board Hydrogen fuel production in vehicles.
Previous studies suggest that the catalyst concentration affects rates of
hydrogen production in metal hydrolysis (Stern, 2014). The study should determine
how rates of hydrogen production compare among NaOH solution concentrations. It
is expected that the rate of hydrogen production in metal hydrolysis will be affected
by NaOH solution concentrations and that higher concentrations of NaOH solution
will increase the rate of production, as seen in similar trials (Stern, 2014).
Methods:
The study was conducted in the Arava Institute for Environmental Studies
Laboratory, at Kibbutz Ketura, Israel. Throughout all times in the study, the
temperature in the lab was kept at 25C. Through a series of repetitions of the metal
hydrolysis process, the tests measured hydrogen production rates at different NaOH
solution concentrations of 0.1M, 0.5M, 1M, and 5M.
Chemical Reactants
Related studies have found Aluminum, as well as Boron, to be promising
candidates for hydrogen production through metal hydrolysis (Abu-Hamed, 2007).
A similar study has also suggested the superiority of NaOH as a catalyst in such a
reaction (Stern, 2014).
The equation below used to calculate the mass of NaOH used to produce
different NaOH concentrations:

4. AIES Independent Study
June 4, 2015
𝑀 =
𝑛
𝑉
=
𝑚/𝑀𝑊
𝑉
(2)
Where M is concentration (mol/L), n is number of moles (mol), V is volume
(L), m is the mass (g), and MW is molecular weight of NaOH (40 g/mol). Calculations
of grams of NaOH per 100mL of water needed for each concentration are as follows:
0.1M =
𝑛
𝑉
=
𝑚/40
0.1 𝑙𝑖𝑡𝑒𝑟
m= 0.4 g NaOH
0.5M =
𝑛
𝑉
=
𝑚/40
0.1 𝑙𝑖𝑡𝑒𝑟
m= 2.0 g NaOH
1.0M =
𝑛
𝑉
=
𝑚/40
0.1 𝑙𝑖𝑡𝑒𝑟
m= 4.0g NaOH
2.0M =
𝑛
𝑉
=
𝑚/40
0.1 𝑙𝑖𝑡𝑒𝑟
m=8.0g NaOH
The mass of Aluminum needed for the chemical reaction was calculated with
Equation 1.
2 Al + 3 H2O  Al2O3 + 3 H2 (1)
(with NaOH as a catalyst)
According to Equation 1, 2 moles of Aluminum produce 3 moles of Hydrogen.
With the assumption of the reaction produces 50 mL of Hydrogen gas, the moles of
Hydrogen were calculated with the following equation:
n=V/MW (3)
Where n is the number of Hydrogen moles, V is the Hydrogen volume in
liters, and the molar mass of Hydrogen is 22.4 g/mol.
n=0.050/22.4 =0.0022 moles of H
Since 2 moles of Aluminum produce 3 moles of Hydrogen, as seen in
Equation 1, the number of aluminum moles were calculated by multiplying the
number of moles of Hydrogen by 2/3. This resulted in 0.0015 moles of Al, which
were converted into mass using Equation 3.
m=0.0015*27=0.04 grams of Al
Apparatus
A calibrated mass scale was used to measure 0.4g of NaOH and 0.04 grams of
Al. NaOH was dissolved into a flask filled with 100mL of distilled water. Care was

5. AIES Independent Study
June 4, 2015
taken when spooning out contents onto wax paper to reduce time in which NaOH
was exposure to air. Al was in the form of aluminum foil. Aluminum foil was cut into
4cm x 2cm rectangles folded three times.
The reactions will take place in an airtight glass jar attached to flexible
rubber tubing. The tubing will be connected to a buret, the bottom end of which will
be submerged in water. Water was extracted to fill a buret tube to the 50mL line. As
the reaction takes place, the hydrogen gas produced will displace water in the buret
tube. Airtight glass jars were filled with enough NaOH solution to submerge the
aluminum foil.
Fig. 2: Testing apparatus; (left to right) Mass scale, NaOH (with red cap), notebook
(for recording water levels and qualitative notes), rubber gloves (for handling
NaOH, Al foil, and byproducts), sitting atop each jack is an airtight glass jar with
rubber tubing running through the water in the beakers to the submerged bottom
end of the burets (which are clamped to upright poles behind)
Data collection
Two identical apparatuses were set up to obtain two simultaneous and
similar repetitions. This process was repeated for NaOH solutions with a
concentration of 0.5M, 1M and 5M.
Rate of Hydrogen production was recorded at intervals of 5 minutes for
NaOH solutions with a concentration of 0.1M; 2 minute intervals for 0.5M, 1M, and

6. AIES Independent Study
June 4, 2015
5M because of the increased rate of H production. Timekeeping was started when
aluminum foil was added to the solution in the first airtight glass jar and the lid
closed. Airtight glass jars were swirled ever 5 minutes or so, to encourage aluminum
foil to completely submerge. Water levels were observed by eye and recorded by
hand. Quantitative recording ended when water levels reached 0mL, after which
some qualitative observations were made.
Data Analysis
The effects of the variable concentration on rates of production were
compared. Results were compared with data from the Stern study of 2014, as well
as other studies of on- board H production technologies and external H production
technologies. Lastly, the practicality of application of this hydrogen production
method for on- onboard vehicles was assessed with comparisons to the capabilities
of gasoline cars.
Results
The results show a positive correlation between NaOH concentration and H
production rate (Fig. 1). The most rapid rate was seen in the NaOH concentration of
2.0M, as expected.
Fig. 3: Hydrogen Production Rate for various NaOH concentrations
This study found the highest rate of H production to be 5.4 mL/min for the 2.0M
NaOH concentrations (Fig. 4 and Table 1). The next fastest rate of H production was
0
10
20
30
40
50
60
1 6 11 16 21 26 31 36 41 46 51 56 61 66
AverageVolumeofHProduced
(mL)
Time (minutes)
0.1M
0.5M
1.0M
2.0M

7. AIES Independent Study
June 4, 2015
1.0M at 1.3 mL /min. The rate for 0.5M was 0.9 mL/min and for 0.1M was 0.6
mL/min.
Fig. 4: Average Hydrogen Production Rate for various NaOH concentrations
0.1M 0.5M 1.0M 2.0M
Avg. Rates
y=0.6482x -
1.7982
y=0.9015x -
3.9785
y=1.3454x -
4.5464
y=5.4264x -
9.9669
Calculated
finish times
(mins) 79.91082999 59.87631725 40.54288687 11.05095459
Table 1: Comparison of Average rates and Calculated finish times
y = 0.6482x - 1.7982
y = 0.9015x - 3.9785
y = 1.3454x - 4.5464
y = 5.4264x - 9.9669
0
50
100
150
200
250
300
350
400
1 6 11 16 21 26 31 36 41 46 51 56 61 66
AverageVolumeofHProduced(mL)
Time (minutes)
0.1M
0.5M
1.0M
2.0M
Linear (0.1M)
Linear (0.5M)
Linear (1.0M)
Linear (2.0M)

8. AIES Independent Study
June 4, 2015
Discussion
Results from this experiment, alone, are not enough – more repetitions
would be needed to confirm the trends, however, in testing, some trends became
evident and these trends are supported by results found in a similar study (Stern,
2014). NaOH concentration did affect the rate of H production in metal hydrolysis
and positively correlated (Fig. 3), as predicted. It is this positive correlation that was
seen previously by Stern (2014) (Appendix).
The unexpected element in the results was the difference between rates. The
rate for 2.0M, the fastest rate, was about 400% faster than the rate for 1.0M, which
is half of the concentration. The rate for 2.0M is also around 600% of the rate for
0.5M, which is only a 400% increase in concentration.
This significant increase in rate of hydrogen production may have resulted
from improperly cleaned equipment in repetitions of 0.1M, 0.5M, and half of the
repetitions for 1.0M. After testing 0.1M, 0.5M, and half of the repetitions of 1.0M, an
orange substance found inside Jar 1 lid (Fig. 5). After cleaning lids and jars, H
production times for 1.0M sped up. Orange substance is likely Al2O3, a byproduct of
the reaction. This substance may have blocked H gas flow or it may have inhibited
the reaction by decreasing unreacted aluminum surface area, as seen in studies on
boron (Wahbeh et al., 2012).
Fig. 5: Both test jars after third trial (May 5, 2015). Byproducts of reaction -
blackened liquid and corroded aluminum foil are visible, as well as orange
substance found inside Jar 1 lid.

9. AIES Independent Study
June 4, 2015
Another trend that became evident was the slower rates seen in Jar 1 in all
tests but those preformed on 0.1M NaOH concentrations. Because the discrepancy
was still seen in testing after the lids and jars were cleaned, though to a much lesser
extent, and because the difference in jar rates was not observed in testing of 0.1M, it
is unlikely that the orange substance was the only cause. There is a possibility that
the differences come from recording errors; visual observation of water levels was
done with two sets of eyes when testing 0.1M, and one set for other concentrations,
with Jar 1 being observed first consistently (though this may have been
counteracted by roughly the same true start time lapses, as aluminum was added to
Jar 1 and then Jar 2). There may also be the possibility of the appearance of a small
leakage in Jar 1, though more testing would be needed to confirm this.
If this research were to continue, testing to attempt to understand these two
deviations may lead to a better understanding of the process, however testing
molarities above 2.0M and at what concentration effects begin to wane, may be
more pertinent to the objectives of this study. This would need to be done with
either a smaller amount of aluminum or a more exact way to record levels, as the
rates are expected to increase dramatically.
Still, even with molarities above 2.0M, it is not predicted that there will be a
sufficient increase in rate to outperform other methods of hydrogen production.
This study found the highest rate of H production to be 5.4 mL/min for the 2.0M
NaOH concentrations and the next fastest rate to be 1.3 mL /min for 1.0M (Fig. 4 and
Table 1). Stern found rates of ~4.9 mL/min for a 2.0M concentration of NaOH
combined with 0.032g of Al (as compared with 0.04g of Al in this study) at 25C
(2014). While the rates found in this study for 2.0M are slightly faster than those
found by Stern, the rates Stern saw at 50C were much faster than either
experiments at 25C. At 50C, rates were seen to be ~16.6 mL/min for 2.0M and
~15.5 mL/min for 1.0M (Stern, 2014). The trend of increased rates of H production
with higher temperatures has been seen with other metals and processes (Gálvez et
al., 2008; Stern, 2014; Vishnevetsky et al., 2011; Wahbeh et al., 2012; Weidenkaff et
al., 2000). The rates found in this study are also far below those found for boron at
very high temperatures has been seen at ~70 ccm, at highest, 6.5 minutes into the
reaction (Wahbeh et al., 2012).
Considering that ~56,000,000 mL of H (5kg) are needed to drive a car 500km
(Abu-Hamed et al., 2007), comparable with gasoline- powered vehicles, over a
million times more H would need to be produced. Though it’s unclear how this type
of expansion would affect rates of production, it is evident such an augmentation of
materials involved in the reaction would make the technology nonviable in
application, on-board vehicles.
Variables other than concentration, such as higher temperatures, metal type,
reactant quantity, and ways to increase surface area, might produce greater
increases in hydrogen production rate and should be studied.

10. AIES Independent Study
June 4, 2015
Conclusion
Hydrolysis, or ‘water splitting’, emits no pollution, and recent studies suggest that
solar energy could be used to recycle the metal oxidized in the process, which could
close the loop of this process and make a storable and transportable, in the form of
Hydrogen (H) fuel form of solar energy, that is more competitive with fossil fuels.
This study investigated efficient hydrogen production, for use on-board vehicles, by
measuring the effects of the catalyst, Sodium Hydroxide (NaOH), concentration on
the rate of production of hydrogen gas. The time required to produce 50mL of H gas
was recorded for exactly calculated amounts of Water, Aluminum foil, and NaOH. A
positive correlation was seen between NaOH concentration and H production rate,
and fastest rate was found in the NaOH concentration of 2.0M (significantly higher
than other tested concentrations). Rates found in this study were not as high as
those found with higher temperatures (Stern, 2014) and with different metals and
temperatures (Wahbeh et al., 2012). While this method may not lead be a practical
alternative to fossil fuels, there are other promising on-board hydrogen production
methods may produce greater increases than seen in this study in hydrogen
production rate and should be studied.
Acknowledgements: Tareq Abu Hamed, Gabi, Avi, Jess, Dan, Alex, Arava Institute
for Environmental Sciences, Kibbutz Ketura
References:
Abu-Hamed, T., Karni, J., & Epstein, M. (2007). The use of boron for thermochemical
storage and distribution of solar energy. Solar Energy, 81:93-101.
Wahbeh,B., Abu Hamed,T., & Kasher, R. (2012). Hydrogen and boric acid production
via boron hydrolysis, Renewable Energy, 48:10-15.
Burke, A., & Gardiner, M. (2005). “Hydrogen Storage Options: Technologies and
Comparisons for Light-duty Vehicle Applications.” Hydrogen Pathways Program
Institute of Transportation Studies University of California-Davis, UCD-ITS-RR-05-
01.
Gálvez, M.E., Frei, A., Albisetti, G., Lunardi, G., & Steinfeld, A. (2008). Solar hydrogen
production via a two-step thermochemical process based on MgO/Mg redox
reactions—thermodynamic and kinetic analyses. Int J Hydrogen Energy, 33:
2880–2890.
Katz, J. (2015). “Global Energy: Where in World Will it Come From?” [Seminar
lecture and PowerPoint]. Denison University.

11. AIES Independent Study
June 4, 2015
MacKay, D.J.C. (2009). Sustainable Energy - without the hot air. Cambridge, England:
UIT.
MacLean, H. L., & Lave, L. B. (2003). Life cycle assessment of Automobile/Fuel
options. Environmental Science & Technology, 37: 5445-5452.
Martınez, S.S., Benites, W.L., Gallegos, A.A., & Sebastian, P.J. (2005). Recycling of
aluminum to produce green energy. Solar Energy Materials and Solar Cells, 88: 237-243.
Mayyas, A., Qattawi, A., Omar, M., & Shan, D. (2012). Design for sustainability in
automotive industry: A comprehensive review. Renewable and Sustainable Energy
Reviews, 16(4), 1845-1862.
Stern, T. “Hydrogen Production by Low Temperature Metal Hydrolysis.” Arava
Institute for Environmental Studies. Advisor: Dr. Tareq Abu Hamed. Ketura, 2014.
Vishnevetsky, I., Epstein, M., Abu-Hamed, T., & Karni, J. (2008). Boron hydrolysis at
moderate temperatures: First step to solar fuel cycle for transportation. Journal of Solar
Energy Engineering (Transactions of the ASME), 130(1)
Vishnevetsky, I., Berman, A., & Epstein, M. (2011). Features of solar
thermochemical redox cycles for hydrogen production from water as a
function of reactants’ main characteristics. Int J Hydrogen Energy, 36: 2817–
2830
Weidenkaff, A., Reller, A., Wokaun, A., & Steinfeld, A. (2000). Thermogravimetric
analysis of the ZnO/Zn water splitting cycle. Thermochimical Acta, 359: 69–75
Yavor, Y., Goroshin, S., Bergthorson, J.M., Frost, D.L., Stowe, R., and Ringuette, S.
(2013). Enhanced hydrogen generation from aluminum water reactions.
International Journal of Hydrogen Energy 38: 14992–15002.

12. AIES Independent Study
June 4, 2015
Appendices
(Stern, 2014)
This study:
0
10
20
30
40
50
60
1 6 11 16 21 26 31 36 41 46 51 56 61 66
AverageVolumeofHProduced
(mL)
Time (minutes)
0.1M
0.5M
1.0M
2.0M
0
5
10
15
20
25
30
35
40
45
50
00:00 05:00 10:00 15:00 20:00 25:00 30:00
Volume(ml)
Time(min)
Hydrogen volume V Time
25C, NaOH
2M
1M
0.5M