Home Tech A new method for capturing carbon from the air using vanadium

A new method for capturing carbon from the air using vanadium

A new method for capturing carbon from the air using vanadium

The research makes a decisive breakthrough in capturing and removing CO2 from the air and curbing climate change

Vanadium is such a visually striking chemical element (due to its spectacular color reflections) that it was named after a goddess. But vanadium also has a perfect level of reactivity – not too much, not too little – making it a good candidate for carbon purification.

Research by scientists at Oregon State University has demonstrated the ability of vanadium peroxide molecules to react with and bind to carbon dioxide (CO2), an important step in improving carbon dioxide removal technologies. of carbon from the atmosphere.

Direct Carbon Capture (DAC)

The study is part of a $24 million federal initiative to develop new methods for direct air capture (DAC) of carbon dioxide, a greenhouse gas produced by the burning of fossil fuels that has been linked to climate change.

Plants that filter carbon from the air are being built around the world, but they are still in their infancy. Technologies for reducing carbon dioxide at the point of entry into the atmosphere, for example in power plants, are more developed. Scientists say both types of carbon capture will likely be necessary if Earth is to avoid the worst consequences of climate change.

In 2021, May Nyman, Terence Bradshaw Professor of Chemistry at the University of Oregon College of Science, was selected as director of one of nine direct air capture projects funded by the Department of Energy. His team is studying how some transition metal complexes can react with air to remove carbon dioxide and convert it into a metal carbonate, similar to that found in many natural minerals.

Transition metals are located near the center of the periodic table and are named for the transition of electrons from low energy states to high energy states and vice versa, which results in characteristic colors. For this study, the scientists chose vanadium, named after Vanadis, the Old Norse name of the Scandinavian goddess of love who was said to be so beautiful that her tears turned to gold.

Nyman explains that carbon dioxide exists in the atmosphere at a density of 400 parts per million. This means that for every million air molecules there are 400 carbon dioxide, or 0.04%.

“The challenge with direct air sensing is to find molecules or materials that are selective enough so that other reactions with more common air molecules, such as reactions with water, do not compete with the reaction with CO2,” explains Nyman. “Our team has synthesized a series of molecules that contain three key components that work together to remove carbon dioxide from the atmosphere.”

The metal of the love goddess Vanadis

One part was vanadium, named for the variety of beautiful colors it can display, and another part was peroxide, which bonded to the vanadium. Because a vanadium peroxide molecule is negatively charged, it needed alkali cations to balance the charge, Nyman explained, and the researchers used alkali cations of potassium, rubidium and cesium for this study.

He added that employees were also trying to replace vanadium with other metals in the same neighborhood on the periodic table.

“Tungsten, niobium and tantalum were not as effective in this chemical form,” Nyman said. “On the other hand, molybdenum was so reactive that it sometimes exploded.”

In addition, the scientists replaced the alkalis with ammonium and tetramethylammonium, the former being slightly acidic. These compounds did not respond at all, a mystery that researchers are still trying to solve.

“And when we removed the peroxide, there wasn’t much reactivity,” Nyman explains. “In this sense, vanadium peroxide has a beautiful purple color that turns to gold when exposed to air and binds to a carbon dioxide molecule.”

He points out that another valuable property of vanadium is that it allows a comparatively low release temperature of around 200 degrees Celsius for the captured carbon dioxide.

“Compared to the almost 700 degrees Celsius that it reaches when it binds to potassium, lithium or sodium, other metals used to fix carbon,” he explains. “The ability to release the captured CO2 allows the carbon capture materials to be reused. The lower the temperature required, the less energy is required and the lower the costs. “Some very ingenious ideas for reusing captured carbon are already being implemented: for example, channeling captured CO2 into a greenhouse to grow plants.”

REFERENCE

Use of vanadium peroxides as materials for direct carbon capture in the air

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