Getting A Grip On CO₂ Capture

The ability to keep CO₂ out of the atmosphere to help prevent climate change is a global issue. The challenge is to use materials that can capture the CO₂ and easily release it for permanent storage.

Researchers at the University of Calgary and University of Ottawa have provided deeper insights to CO₂ capture by "seeing" the exact sites where CO₂ is held in a capture material. Their discovery, published in the prestigious journal Science, will allow scientists to design better materials to capture more CO₂.

The findings can be likened to learning about a better fit between a baseball glove and a ball in order to improve performance. Different gloves fit different size of balls better and it's easier to catch a ball with a glove that is moulded to it. In the case of CO₂ capture, think of the ball as the CO₂ and the glove as the material that houses the CO₂.

"We have pinpointed where the CO₂ molecule is held by direct experimental visualization (X-ray crystallography) and, through computer modeling, we can see how every 'finger' contributes to holding the CO₂ in place," says co-author Dr. George Shimizu, a U of C chemistry professor whose research was funded by the U of C's Institute for Sustainable Energy, Environment and Economy and NSERC.

What's also significant about this discovery is the exceptional correlation between experiment and computer simulation. Computer simulations can now be more confidently applied to predict the CO₂ capture ability of materials on the computer before they are made in the laboratory. "The detailed computational analysis of how CO₂ is captured in this material provides new directions for designing improved materials," says Dr. Tom Woo, an associate chemistry professor and Canada Research Chair at the University of Ottawa, who is a co-author of the work along with his graduate student Peter Boyd.

This research may be used for a variety of applications. "We could ultimately see this process helping to mitigate greenhouse gas emissions on the top of coal burning flue stacks or it could be used to help remove CO₂ from unconventional natural gas reservoirs," says Dr. Ramanathan Vaidhyanathan, the paper's first author and research associate at the U of C.

Current methods of CO₂ capture take place by bubbling CO₂ through a liquid solution, which strongly binds to the CO₂, a process called amine scrubbing. The major downside of this technology is that to recycle to the absorbing solution and release the CO₂ , heating to over 100 C is required. Most estimates say to capture CO₂ from a coal-fired power plant by this technique would cost about one-quarter of the plant's energy production.

The article, "Direct observation and quantification of CO₂ binding within an amine-functionalized nanoporous solid", was published in Science and written by Ramanathan Vaidhyanathan, Simon S. Iremonger and George K. H. Shimizu from the University of Calgary and Peter G. Boyd, Saman Alavi, Tom K. Woo from the University of Ottawa.

SOURCE: University of Calgary