New catalyst transforms carbon dioxide into sustainable byproduct
The carbon capture method works by using carbon to make acetic acid

Date:
May 3, 2023
Source:
Northwestern University
Summary:
-Electrocatalyst achieves record-breaking selectivity toward
desired product, a key step in expanding production -Acetic acid,
found in vinegar, is traditionally extracted from fossil fuels
for use in paint and other product feedstock.


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FULL STORY ==========================================================================
The need to capture CO2 and transport it for permanent storage or
conversion into valued end uses is a national priority recently identified
in the Bipartisan Infrastructure Law to move toward net-zero greenhouse
gas emissions by 2050.

Now, Northwestern University researchers have worked with an international
team of collaborators to create acetic acid out of carbon monoxide derived
from captured carbon. The innovation, which uses a novel catalyst created
in the lab of professor Ted Sargent, could spur new interest in carbon
capture and storage.

"Carbon capture is feasible today from a technical point of view,
but not yet from an economic point of view," Sargent said. "By
using electrochemistry to convert captured carbon into products with established markets, we provide new pathways to improving these economics,
as well as a more sustainable source for the industrial chemicals that we
still need." The paper was published today (May 3) in the journal Nature.

Sargent, the paper's corresponding author, is Northwestern's Lynn Hopton
Davis and Greg Davis Professor of Chemistry at the Weinberg College of
Arts and Sciences and a professor of electrical and computer engineering
at the McCormick School of Engineering. His team has a track record of
using electrolyzers -- devices in which electricity drives a desired
chemical reaction forward -- to convert captured carbon into key
industrial chemicals, including ethylene and propanol.

Though acetic acid may be most familiar as the key component in household vinegar, recent University of Toronto Ph.D. recipient Josh Wicks, one
of the paper's four co-lead authors, said this use accounts for only a
small proportion of what it's used for.

"Acetic acid in vinegar needs to come from biological sources via
fermentation because it's consumed by humans," Wicks said. "But about
90% of the acetic acid market is for feedstock in the manufacture of
paints, coatings, adhesives and other products. Production at this scale
is primarily derived from methanol, which comes from fossil fuels."
Lifecycle assessment databases showed the team that for every kilogram
of acetic acid produced from methanol, the process releases 1.6 kg of CO2.

Their alternative method takes place via a two-step process: first,
captured gaseous CO2 is passed through an electrolyzer, where it reacts
with water and electrons to form carbon monoxide (CO). Gaseous CO is then passed through a second electrolyzer, where another catalyst transforms
it into various molecules containing two or more carbon atoms.

"A major challenge that we face is selectivity," Wicks said. "Most of
the catalysts used for this second step facilitate multiple simultaneous reactions, which leads to a mix of different two-carbon products that
can be hard to separate and purify. What we tried to do here was set up conditions that favor one product above all others." Vinayak Dravid,
another senior author on the paper and the Abraham Harris Professor
of Materials Science and Engineering, is the founding director of the Northwestern University Atomic and Nanoscale Characterization (NUANCE)
Center, which allowed the team to access diverse capabilities for atomic-
and electronic-scale measurements of materials.

"Modern research problems are complex and multifaceted and require
diverse yet integrated capabilities to analyze materials down to
the atomic scale," Dravid said. "Colleagues like Ted present us with challenging problems that stimulate our creativity to develop novel
ideas and innovative characterization methods." The team's analysis
showed that using a much lower proportion of copper (approximately 1%)
compared with previous catalysts would favor the production of just acetic acid. It also showed that elevating the pressure to 10 atmospheres would
enable the team to achieve record-breaking efficiency.

In the paper, the team reports a faradic efficiency of 91%, meaning that
91 out of every 100 electrons pumped into the electrolyzers end up in
the desired product -- in this case, acetic acid.

"That's the highest faradic efficiency for any multi-carbon product at a scalable current density we've seen reported," Wicks said. "For example, catalysts targeting ethylene typically max out around 70% to 80%, so
we're significantly higher than that." The new catalyst also appears
to be relatively stable: while the faradic efficiency of some catalysts
tend to degrade over time, the team showed that it remained at a high
level of 85% even after 820 hours of operation.

Wicks hopes that the elements that led to the team's success -- including
a novel target product, a slightly increased reaction pressure, and a
lower proportion of copper in the catalyst -- inspire other teams to
think outside the box.

"Some of these approaches go against the conventional wisdom in this
field, but we showed that they can work really well," he said. "At
some point, we're going to have to decarbonize all the elements of
chemical industry, so the more different pathways we have to useful
products, whether it's ethanol, propylene or acetic acid, the better."
The research was funded by the National Key R&D Program of China (grant
number 2022YFC2106000, 2022YFA1505100 and 2020YFA0715000), the National
Natural Science Foundation of China (grant numbers 11874164, 52006085, BE3250011, 52127816, 51832004, 51972129 and 52272202) and the Innovation
Fund of Wuhan National Laboratory for Optoelectronics. Also supporting
is the China Postdoctoral Science Foundation (grant numbers 2019TQ0104
and 2020M672343), the) and Shanghai Jiao Tong University (grant number WH220432516). The Natural Sciences and Engineering Research Council
of Canada (NSERC) Discovery program (grant number RGPIN-2017-06477)
and the Ontario Research Fund (grant number ORF-RE08-034) provided
funding. Finally, the Marsden Fund Council for Government funding
(grant number 21-UOA-237) and the Catalyst: Seeding General Grant (grant
number 22-UOA-031-CGS), managed by the Royal Society Te Ap?rangi funded
the research.

This work made use of the EPIC facility of Northwestern University's
NUANCE Center, which has received support from the SHyNE Resource (grant
number NSF ECCS-2025633), the IIN and Northwestern's MRSEC programme
(grant number NSF DMR-1720139).

* RELATED_TOPICS
o Matter_&_Energy
# Organic_Chemistry # Graphene # Electronics #
Nanotechnology
o Earth_&_Climate
# Air_Quality # Global_Warming # Forest # Geochemistry
* RELATED_TERMS
o Acid o Fossil_fuel o Fossil o Alcohol_fuel o Economic_growth
o Hurricane_Emily_(2005) o Citric_acid o Agriculture

========================================================================== Story Source: Materials provided by Northwestern_University. Original
written by Win Reynolds. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jian Jin, Joshua Wicks, Qiuhong Min, Jun Li, Yongfeng Hu, Jingyuan
Ma, Yu
Wang, Zheng Jiang, Yi Xu, Ruihu Lu, Gangzheng Si, Panagiotis
Papangelakis, Mohsen Shakouri, Qunfeng Xiao, Pengfei Ou, Xue Wang,
Zhu Chen, Wei Zhang, Kesong Yu, Jiayang Song, Xiaohang Jiang, Peng
Qiu, Yuanhao Lou, Dan Wu, Yu Mao, Adnan Ozden, Chundong Wang, Bao Yu
Xia, Xiaobing Hu, Vinayak P. Dravid, Yun-Mui Yiu, Tsun-Kong Sham,
Ziyun Wang, David Sinton, Liqiang Mai, Edward H. Sargent, Yuanjie
Pang. Constrained C2 adsorbate orientation enables CO-to-acetate
electroreduction. Nature, 2023; DOI: 10.1038/s41586-023-05918-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230503121328.htm

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