Amines attached to spherical fullerenes (Bucky spheres) are able to absorb carbon dioxide from emissions from industrial plants and natural gas wells, according to a new study.
[by Dr. Nachmani Moshe]
![Molecules of carbon-60, known as amines attached to spherical fullerenes (Bucky spheres) are able to absorb carbon dioxide from emissions from industrial plants and natural gas wells, according to a new study. Also called Becky balls, combined with amines to obtain a compound that absorbs carbon dioxide, which is a greenhouse gas, in an amount equal to a fifth of its weight. The material has the potential to be used as an environmentally friendly solution to capture carbon from emissions originating from natural gas wells and industrial plant chimneys. [Courtesy of Barron Research Group]](https://www.hayadan.org.il/images/content3/2014/12/1208_CARBON-1-RN.jpg)
Experiments conducted at pressure ranges of 50-1 atmospheres demonstrated that the new compound developed at Rice University succeeds in capturing carbon dioxide in an amount equal to a fifth of its weight, without capturing measurable amounts of methane. In the laboratory of chemist Andrew Barron, it was discovered as part of a proof-of-concept type of research that amine-rich compounds are particularly effective in capturing greenhouse gases when combined with molecules of fullerene-60. The findings of the article were published in the scientific journal Scientific Reports.
"We had two goals," says the lead researcher. "The first, to develop a compound that will be completely selective in its reaction with carbon
dioxide compared to its reaction with methane at any pressure and at any temperature. The second goal was to reduce the high temperature required by other amine solutions in order to release the trapped carbon dioxide. To my delight, we were able to realize both of these goals."
Carbon-60, the football-shaped molecule also known as beckminsterfullerene ("Becky ball"), was discovered at Rice University by Nobel laureates Richard Smalley, Robert Curl, and Harold Kroto in 1985. The absolute curvature of Becky balls may make them the best option more for binding amine molecules that capture carbon dioxide and at the same time, allow the desired methane gas to pass through them. The researchers used the Becky spheres as link points between the different amines, which are nitrogen-based molecules. The researchers created a warm, spongy material that contains hydrophobic (water-avoiding) amines that push the hydrophilic amines (water-seeking) out to the surface, where the carbon dioxide molecules can bind and be captured by the exposed nitrogen atoms. When the researchers started connecting carbons and amines several years ago, they noticed an interesting result: a flat graphene molecule was able to absorb carbon dioxide well, single-walled nanotubes absorbed the gas to a better degree, and thinner nanotubes did at the best level. "This result suggests that the curvature was important for the level of the link," the researcher points out. "The compound carbon-60, being a perfect sphere, has the highest possible sphericality of all substances based on carbon atoms alone."
The researcher noted that the new compound achieved better results compared to other candidates capable of capturing carbon and which are based on metal-organic frameworks (MOFs). "Our material is as effective as the best existing material, but it is much more selective than that. The methane gas is simply not absorbed into it," said the researcher. In addition, the new compound is also able to absorb wet carbon dioxide.
The lead researcher says that the ability of the compound to release the gas efficiently in favor of its reuse is also important. "We noticed a long time ago that if we attach amine groups to carbon nanotubes or graphene, they reduce the temperature at which carbon dioxide dissolves," explains the lead researcher. Industrial purification facilities for amine-based materials must be heated to a temperature of 140 degrees Celsius in order to release the trapped carbon dioxide; Reducing this temperature will probably lead to saving the required energy and reducing the overall financial cost.
"Compared to the cost of the reliable materials in use today, the cost of carbon-60 is admittedly more expensive," explains the researcher. "However, the energy costs will be less since you need less energy to release the trapped gas." He explains that amine purifiers cause the loss of these substances during heating, so it is necessary to renew them regularly, and this limitation causes higher costs. The researchers continue and try to find ways to improve the absorption capacity and increase its rate.
