Page 59 - Plastics News September 2019

TECHNOLOGY

Reactor turns greenhouse gas into pure liquid fuel

common greenhouse gas could be repurposed in an the reaction. "Bismuth is a very heavy atom, compared to
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electrolyzer that uses renewable electricity to produce "Its mobility is much lower, particularly under reaction
pure liquid fuels. The catalytic reactor developed by the conditions. So that stabilizes the catalyst." He noted
Rice University lab of chemical and biomolecular engineer the reactor is structured to keep water from contacting
+DRWLDQ :DQJ XVHV FDUERQ GLR[LGH DV LWV IHHGVWRFN DQG the catalyst, which also helps preserve it. Xia can make
LQ LWV ODWHVW SURWRW\SH SURGXFHV KLJKO\ SXULÀHG DQG KLJK the nanomaterials in bulk. "Currently, people produce
concentrations of formic acid.Formic acid produced FDWDO\VWV RQ WKH PLOOLJUDP RU JUDP VFDOHV KH VDLG :H
by traditional carbon dioxide devices needs costly and developed a way to produce them at the kilogram scale.
HQHUJ\ LQWHQVLYH SXULILFDWLRQ VWHSV :DQJ VDLG 7KH That will make our process easier to scale up for industry."
direct production of pure formic acid solutions will The polymer-based solid electrolyte is coated with sulfonic
help to promote commercial carbon dioxide conversion acid ligands to conduct positive charge or amino functional
technologies.
groups to conduct negative ions. "Usually people reduce
carbon dioxide in a traditional liquid electrolyte like
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conducted, but pure water electrolyte is too resistant.
You need to add salts like sodium chloride or potassium
bicarbonate so that ions can move freely in water. "But
when you generate formic acid that way, it mixes with
the salts," he said. "For a majority of applications you
have to remove the salts from the end product, which
takes a lot of energy and cost. So we employed solid
electrolytes that conduct protons and can be made of
insoluble polymers or inorganic compounds, eliminating
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in January, and his group pursue technologies that turn the product chamber determines the concentration of the
greenhouse gases into useful products. In tests, the new solution. Slow throughput with the current setup produces
HOHFWURFDWDO\VW UHDFKHG DQ HQHUJ\ FRQYHUVLRQ HIÀFLHQF\ RI a solution that is nearly 30% formic acid by weight, while
about 42%. That means nearly half of the electrical energy IDVWHU ÁRZV DOORZ WKH FRQFHQWUDWLRQ WR EH FXVWRPL]HG
can be stored in formic acid as liquid fuel."Formic acid The researchers expect to achieve higher concentrations
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can generate electricity and emit carbon dioxide -- which bring out pure formic acid vapors. The Rice lab worked
you can grab and recycle again. "It's also fundamental in with Brookhaven National Laboratory to view the process
the chemical engineering industry as a feedstock for other in progress. "X-ray absorption spectroscopy, a powerful
chemicals, and a storage material for hydrogen that can technique available at the Inner Shell Spectroscopy (ISS)
hold nearly 1,000 times the energy of the same volume beamline at Brookhaven Lab's National Synchrotron Light
RI K\GURJHQ JDV ZKLFK LV GLIÀFXOW WR FRPSUHVV KH VDLG Source II, enables us to probe the electronic structure
"That's currently a big challenge for hydrogen fuel-cell of electrocatalysts in operando -- that is, during the
cars."Two advances made the new device possible, said actual chemical process," said co-author Eli Stavitski,
lead author and Rice postdoctoral researcher Chuan lead beamline scientist at ISS. "In this work, we followed
;LD 7KH ÀUVW ZDV KLV GHYHORSPHQW RI D UREXVW WZR bismuth's oxidation states at different potentials and were
dimensional bismuth catalyst and the second a solid-state able to identify the catalyst's active state during carbon
electrolyte that eliminates the need for salt as part of dioxide reduction.

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61 September 2019 Plastics News