A chemical element so visually striking that it was named for a goddess shows a “Goldilocks” level of reactivity — neither an excessive amount of nor too little — that makes it a powerful candidate as a carbon scrubbing tool.
The element is vanadium, and research by Oregon State University scientists has demonstrated the power of vanadium peroxide molecules to react with and bind carbon dioxide — a crucial step toward improved technologies for removing carbon dioxide from the atmosphere.
The study is a component of a $24 million federal effort to develop latest methods for direct air capture, or DAC, of carbon dioxide, a greenhouse gas that is produced by the burning of fossil fuels and is related to climate change.
Facilities that filter carbon from the air have begun to spring up across the globe but they’re still of their infancy. Technologies for mitigating carbon dioxide at the purpose of entry into the atmosphere, reminiscent of at power plants, are more well developed. Each kinds of carbon capture will likely be needed if the Earth is to avoid the worst outcomes of climate change, scientists say.
In 2021 Oregon State’s May Nyman, the Terence Bradshaw Chemistry Professor within the College of Science, was chosen because the leader of considered one of nine direct air capture projects funded by the Department of Energy. Her team is exploring how some transition metal complexes can react with air to remove carbon dioxide and convert it to a metal carbonate, just like what’s present in many naturally occurring minerals.
Transition metals are situated near the middle of the periodic table and their name arises from the transition of electrons from low energy to high energy states and back again, giving rise to distinctive colours. For this study, the scientists landed on vanadium, named for Vanadis, the old Norse name for the Scandinavian goddess of affection said to be so beautiful her tears turned to gold.
Nyman explains that carbon dioxide exists within the atmosphere at a density of 400 parts per million. Which means for each 1 million air molecules, 400 of them are carbon dioxide, or 0.04%.
“A challenge with direct air capture is finding molecules or materials which can be selective enough, or other reactions with more abundant air molecules, reminiscent of reactions with water, will outcompete the response with CO2,” Nyman said. “Our team synthesized a series of molecules that contain three parts which can be necessary in removing carbon dioxide from the atmosphere, they usually work together.”
One part was vanadium, so named due to range of gorgeous colours it could exhibit, and one other part was peroxide, which bonded to the vanadium. Because a vanadium peroxide molecule is negatively charged, it needed alkali cations for charge balance, Nyman said, and the researchers used potassium, rubidium and cesium alkali cations for this study.
She added that the collaborators also tried substituting other metals from the identical neighborhood on the periodic table for vanadium.
“Tungsten, niobium and tantalum weren’t as effective on this chemical form,” Nyman said. “Alternatively, molybdenum was so reactive it exploded sometimes.”
As well as, the scientists substituted ammonium and tetramethyl ammonium, the previous of which is mildly acidic, for the alkalis. Those compounds didn’t react in any respect, a puzzler the researchers are still trying to grasp.
“And once we removed the peroxide, again, not a lot reactivity,” Nyman said. “On this sense, vanadium peroxide is an exquisite, purple Goldilocks that becomes golden when exposed to air and binds a carbon dioxide molecule.”
She notes that one other invaluable characteristic of vanadium is that it allows for the comparatively low release temperature of about 200 degrees Celsius for the captured carbon dioxide.
“That is in comparison with almost 700 degrees Celsius when it’s bonded to potassium, lithium or sodium, other metals used for carbon capture,” she said. “With the ability to rerelease the captured CO2 enables reuse of the carbon capture materials, and the lower the temperature required for doing that, the less energy that is needed and the smaller the associated fee. There are some very clever ideas about reuse of captured carbon already being implemented — for instance, piping the captured CO2 right into a greenhouse to grow plants.”
Other Oregon State authors on the paper included Tim Zuehlsdorff, assistant professor of theoretical/physical chemistry, and postdoctoral researcher Eduard Garrido.
“I’m also really pleased with the exertions of the graduate students in my lab, Zhiwei Mao and Karlie Bach, and undergraduate Taylor Linsday,” Nyman said. “It is a brand latest area for my lab, in addition to for Tim Zuehlsdorff, who supervised Ph.D. student Jacob Hirschi on the computational studies to clarify the response mechanisms. Starting a brand new area of study involves many unknowns.”
Eric Walter of the Pacific Northwest National Laboratory and Casey Simons of the University of Oregon also took part within the study, which was published in Chemical Science, the flagship journal of the Royal Society of Chemistry.
