This
is an important advance that promises to make hydrogen reforming from
fossil fuels a viable option on a technical basis. We get assured
clean hydrogen.
There
is plenty of other issues that could well prevent hydrogen technology
from ever been our first choice in transportation. However,
deliverability has always been desirable.
This
is not complete as yet but we are definitely on the right road to a
useful solution for clean hydrogen at least.
Durham NC (SPX) May 24, 2013
Duke University
engineers have developed a novel method for producing clean hydrogen,
which could prove essential to weaning society off of fossil fuels
and their environmental implications.
While hydrogen is
ubiquitous in the environment, producing and collecting molecular
hydrogen for transportation and industrial uses is expensive and
complicated. Just as importantly, a byproduct of most current methods
of producing hydrogen is carbon monoxide, which is toxic to humans
and animals.
The Duke engineers,
using a new catalytic approach, have shown in the laboratory that
they can reduce carbon monoxide levels to nearly zero in the presence
of hydrogen and the harmless byproducts of carbon dioxide and water.
They also demonstrated that they could produce hydrogen by
reforming fuel at much lower temperatures than conventional
methods, which makes it a more practical option.
Catalysts are agents
added to promote chemical reactions. In this case, the catalysts were
nanoparticle combinations of gold and iron oxide (rust), but not in
the traditional sense.
Current methods depend
on gold nanoparticles' ability to drive the process as the sole
catalyst, while the Duke researchers made both the iron oxide and
the gold the focus of the catalytic process.
"Our ultimate
goal is to be able to produce hydrogen for use in fuel cells,"
said Titilayo "Titi" Shodiya, a graduate student working in
the laboratory of senior researcher Nico Hotz, assistant professor of
mechanical engineering and materials science at Duke's Pratt School
of Engineering. "Everyone is interested in sustainable and
non-polluting ways of producing useful energy without fossil fuels,"
said Shodiya, the paper's first author.
Fuel cells produce
electricity through chemical reactions, most commonly involving
hydrogen. Also, many industrial processes require hydrogen as a
chemical reagent and vehicles are beginning to use hydrogen as a
primary fuel source.
"We were able
through our system to consistently produce hydrogen with less than
0.002 percent (20 parts per million) of carbon monoxide,"
Shodiya said.
The Duke researchers
achieved these levels by switching the recipe for the nanoparticles
used as catalysts for the reactions to oxidize carbon monoxide in
hydrogen-rich gases. Traditional methods of cleaning hydrogen, which
are not nearly as efficient as this new approach, also involve
gold-iron oxide nanoparticles as the catalyst, the researchers said.
"It had been
assumed that the iron oxide nanoparticles were only 'scaffolds'
holding the gold nanoparticles together, and that the gold was
responsible for the chemical reactions," Sodiya said. "However,
we found that increasing the surface area of the iron oxide
dramatically increased the catalytic activity of the gold."
One of the newest
approaches to producing renewable energy is the use of
biomass-derived alcohol-based sources, such as methanol. When
methanol is treated with steam, or reformed, it creates a
hydrogen-rich mixture that can be used in fuel cells.
"The main problem
with this approach is that it also produces carbon monoxide, which
is not only toxic to life, but also quickly damages the catalyst on
fuel cell membranes that are crucial to the functioning of a fuel
cell," Hotz said. "It doesn't take much carbon monoxide to
ruin these membranes."
The researchers ran
the reaction for more than 200 hours and found no reduction in the
ability of the catalyst to reduce the amount of carbon monoxide in
the hydrogen gas.
"The mechanism
for this is not exactly understood yet. However, while current
thinking is that the size of the gold particles is key, we believe
the emphasis of further research should focus on iron oxide's role in
the process," Shodiya said.
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