New chemical structures show vastly improved carbon capture ability

This study focused on titanium peroxide, building on their earlier work on vanadium peroxide. The research is part of a larger federal effort to innovate new methods and materials for direct air capture (DAC) of carbon dioxide produced by burning fossil fuels.

The findings, led by May Nyman and Karlie Bach of OSU’s College of Science, were published today in Materials Chemistry.

In 2021, Nyman, the Terence Bradshaw Professor of Chemistry in the College of Science, was selected to lead one of nine direct air capture projects funded by the Department of Energy with an initial investment of $24 million. Her team is exploring how some transition metal complexes react with air, removing carbon dioxide and converting it into metal carbonates, similar to those found in many natural minerals.

Transition metals, located near the center of the periodic table, get their name from the transition of electrons from lower energy states to higher energy states and back again, resulting in their unique colors.

Facilities to filter carbon dioxide from the air are still in their infancy. Technologies to reduce CO2 emissions as they enter the atmosphere, such as from power plants, are more mature. Scientists say both types of carbon capture may be needed if the planet is to avoid the worst consequences of climate change.

There are currently 18 active direct air capture plants operating in the United States, Canada and Europe, with plans to add 130 more globally. Challenges with direct air capture include high cost and high energy requirements compared to treating industrial waste gases. Additionally, the concentration of carbon dioxide in the atmosphere is as low as 4 parts per million, which challenges the performance of carbon capture materials.

“We chose to study titanium because it is 100 times cheaper than vanadium, more abundant, more environmentally friendly, and already widely used in industrial applications,” said Bach, a graduate student in Nieman’s lab. “It is on the periodic table of elements. It’s also in close proximity to vanadium, so we hypothesized that the carbon capture behavior might be similar enough to vanadium to be effective.”

Bach, Niemann and other members of the research team made several new tetraperoxytitanate structures – titanium atoms coordinated with four peroxide groups – that showed different abilities to scavenge carbon dioxide from the air. . Since the peroxide groups are effective oxidizing agents, tetraperoxy structures tend to be highly reactive.

Related peroxytitanates have been investigated for potential use in catalysis, environmental chemistry, and materials science. However, the tetraperoxotitanate in this study was never ultimately synthesized. Bach was able to use inexpensive materials to perform high-yield chemical reactions.

“Our favorite carbon-trapping structure we found is potassium tetrapoxytitanate, which is very unique because it turns out it’s also a peroxygen solvate,” Bach said. “This means that in addition to peroxide binding to titanium In addition, it also contains hydrogen peroxide in its structure, which we think is why it is so active.”

The measured carbon capture capacity is approximately 8.5 millimoles of carbon dioxide per gram of potassium tetrapoxytitanate, approximately twice that of vanadium peroxide.

“Titanium is a cheaper, safer material with significantly higher capacity,” Bach said.

Named after the Titans of Greek mythology, titanium is as strong as steel but much lighter. Non-toxic and non-corrosive, it is the ninth most abundant element in the earth’s crust and can be found in trace amounts in rocks, soil, plants and even the human body.

Other OSU authors on the paper include assistant professors Tim Zuehlsdorff and Konstantinos Goulas, postdoctoral researcher Eduard Garrido Ribó, graduate students Jacob Hirschi, Zhiwei Mao and Makenzie Nord, and crystallographer Lev Zakharov, interim manager of the OSU X-ray Diffraction Facility.

The Murdoch Charitable Trust also supported the research through an instrument grant.