The Catalyst Review September 2019 - 5

PROCESS NEWS
Selenium Anchors Could Improve Durability of Platinum Fuel Cell Catalyst...
Platinum has long been used as a catalyst to enable the oxidation reduction reaction at the center of fuel cell technology. But the
metal's high cost is one factor that has hindered fuel cells from competing with cheaper ways of powering automobiles and homes.
Now researchers at the Georgia Institute of Technology have developed a new platinum-based catalytic system that is far more
durable than traditional commercial systems and has a potentially longer lifespan. The new system could, over the long term, reduce
the cost of producing fuel cells.
The researchers described a possible new way to solve one of the key causes of degradation of platinum catalysts, sintering. To
reduce such sintering, the researchers devised a method to anchor the platinum particles to their carbon support material using
bits of the element selenium. The process starts by loading nanoscale spheres of selenium onto the surface of a commercial carbon
support. The selenium is then melted under high temperatures so that it spreads and uniformly covers the surface of the carbon.
Then, the selenium is reacted with a salt precursor to platinum to generate particles of platinum smaller than two nanometers in
diameter and evenly distributed across the carbon surface. The covalent interaction between the selenium and platinum provides a
strong link to stably anchor the platinum particles to the carbon.
Because of the increased specific surface area of the nanoscale platinum, the new catalytic system initially showed catalytic activity
three and a half times higher than the pristine value of a state-of-the-art commercial platinum-carbon catalyst. Then, the research
team tested the catalytic system using an accelerated durability test. Even after 20,000 cycles of electropotential sweeping, the new
system still provided a catalytic activity more than three times that of the commercial system. They found that the selenium anchors
were effective in keeping most of the platinum particles in place. Source: Georgia Tech, 9/5/2019.
Cheap Water Treatment...
A team led by Anna Śrębowata, professor at the IPC (Institute
of Physical Chemistry, Polish Academy of Sciences) has
improved a method of catalytic hydrotreatment, that is,
transforming trichloroethane (TCE) into hydrocarbons that
are environmentally less harmful. TCE used to be commonly
used in, amongst others, organic syntheses, dry cleaning and
for the industrial degreasing of metals during their processing.
Due to its negative impact, its use has been officially banned
since 2016. However, considering its stability, it may remain in
both the water and soil for many years to come, explains MSc.
Emil Kowalewski, a member of the team that developed the
innovative method of removing this compound from water.
"Today we deal with such compounds mainly by the process
of sorption. However, in this way we're only transferring the
threat from one place to another. An attractive solution seems
to be catalytic hydrotreatment, i.e. transforming the TCE into
less harmful hydrocarbons. However, in order to fully exploit
the potential of this method, it was necessary to develop an
efficient, stable and cheap catalyst," says Dr. Anna Śrębowata,
professor at the IPC. "Previously, we carried out research with
palladium catalysts. They were effective but expensive," notes
Emil Kowalewski. The new nickel catalysts, developed at the IPC
PAS, allow for a cheap and effective method of conducting the
process of water treatment in flow mode, and at the same time
they are easy to synthesize. "Using a catalyst in which nickel
nanoparticles with a diameter of about 20 nm are deposited
on the surface of activated carbon, we combine the sorption
properties of carbon and the catalytic activity of nickel," explains
Kowalewski. In their research, the scientists from the IPC PAS
also showed that nickel nanoparticles deposited on activated
carbon with a partially ordered structure show higher activity
and stability than an analogous catalyst based on a support with
amorphous structure. Source: Phys.org, 9/9/2019.
The Catalyst Review

September 2019

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The Catalyst Review September 2019

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