Release Subtitle:
Scientists report hitherto unobserved high-performance CO2 adsorption in zeolites at room temperature, opening doors to applications in air purification
Release Summary Text:
Reducing the amount of CO2 in our environment is crucial for mitigating climate change and needs materials that can adsorb CO2 from air under ambient conditions. In a new study, scientists from Japan explore the CO2
adsorption properties of zeolite, which has been overlooked in this
regard, and report an unprecedented selective adsorption behavior in the
extremely lower pressure region and at room temperature, paving the way
for its future applications in air purification.
Full text of release:
It is now well known that carbon dioxide is the biggest contributor to
climate change and originates primarily from burning of fossil fuels.
While there are ongoing efforts around the world to end our dependence
on fossil fuels as energy sources, the promise of green energy still
lies in the future. Can something be done in the meantime to reduce the
concentrations of CO2 in the atmosphere?
It would, in fact, be great if the CO2 in the atmosphere could simply be adsorbed! Turns out, this is exactly what direct air capture (DAC), or the capture of CO2 under ambient conditions, aims to do. However, no such material with the ability to adsorb CO2 efficiently under DAC conditions has so far been developed. “It is well known that CO2 is acidic in nature. Therefore, materials with basic nature are generally utilized as adsorbents for CO2. However, that often leads to corrosion of the system and is also not suitable for recycling the adsorbed CO2,” explains Professor Yasushige Kuroda from Okayama University, Japan, who conducts research on surface chemistry.
Against this backdrop, in a recent study published in the Journal of
Materials Chemistry A, scientists from Okayama University and Japan
Synchrotron Radiation Research Institute (JASRI) led by Prof. Kuroda
explored the adsorption properties of a material that has so far
remained an “underdog”: zeolites (minerals containing mainly aluminum
and silicon oxides). “Zeolite materials have received little attention
as adsorbents owing to their low CO2
adsorption capacity at room temperature and in the lower pressure
adsorption region, as well as their poor selectivity over nitrogen,”
says Prof. Kuroda.
In their study, Prof. Kuroda and his team designed an ion-exchanging
method of zeolite with alkaline-earth ions and achieved a remarkably
high CO2
adsorption under ambient conditions. The team specifically chose an
A-type zeolite (silicon/aluminum ratio of 1) because of its appropriate
pore size for adsorbing CO2,
while the alkaline-earth ion exchange imparted a large electric field
strength that, supposedly, acted as a driving force for the adsorption.
Scientists chose a doubly charged calcium ion (Ca2+)
as the exchange ion since it allowed for the greatest amount of
adsorption. In fact, the adsorbed volume noted was the largest amount of
CO2 to have ever been adsorbed by any zeolite system, surpassing that for other materials under similar conditions!
To investigate the underlying adsorption mechanism, the scientists
carried out far-infrared (far-IR) measurements and backed them up with
density functional theory (DFT) calculations. The far-IR spectra, which
detected the vibrational modes due to Ca2+-zeolite vibration, showed a distinct shift towards longer wavelengths following CO2
adsorption, a feature scientists could not recognize in other samples,
e.g. Na-ion exchanged A-type zeolite. They further verified their
observation with a model that showed good agreement with DFT
calculations.
Moreover, the scientists were able to completely desorb the adsorbed CO2
and recover the original sample and its specific adsorption properties.
In addition, the sample showed a superior selective adsorption of CO2 from other gases after the scientists examined the separation of CO2 using a model gas that emulated ambient air in its composition.
The findings thus bring zeolites to the forefront as an efficient adsorbent of CO2
under ambient conditions, a feat previously thought unachievable with
these systems. “Our work can open doors to potentially novel
applications of zeolites, such as in the cleaning of air inside
semi-closed spaces including space shuttles, submarines, and concert
halls, and as an adsorbent material in the anesthetic process,”
speculates Prof. Kuroda excitedly.
One thing is for sure, though: chemists will never look at zeolite in the same way again.
Release URL:
https://www.eurekalert.org/pub_releases/2021-05/ou-zth050521.php
Reference:
Title of original paper:Unprecedented CO2 adsorption behaviour by 5A-type zeolite discovered in lower pressure region and at 300 K
Journal: Journal of Materials Chemistry A
DOI: http://dx.doi.org/10.1039/d0ta09944a
Contact Person: KURODA Yasushige
KURODA Yasushige is a Professor at the Department of Chemistry at Okayama University, Japan since 2004. He obtained his D.Sc. from Hiroshima University, Japan. His research interests comprise surface chemistry of metal oxides, specific adsorption and activation features of metal-ion-exchanged zeolites for small inorganic molecules and analysis of catalyst surfaces. As a senior and reputed researcher, Prof. Kuroda has 146 publications to his credit with over 3000 citations.
https://www.okayama-u.ac.jp/eng/research_highlights/index_id134.html
0 件のコメント:
コメントを投稿