Nanomaterial to separate and store CO₂ emissions

Researchers at the University of Adelaide have developed a nanomaterial that could help reduce carbon dioxide (CO₂) emissions from coal-fired power stations. Their work has been described in the Journal of the American Chemical Society.

“A considerable amount of Australia’s - and the world’s - carbon dioxide emissions come from coal-fired power stations,” explained Associate Professor Christopher Sumby, project leader and ARC Future Fellow in the university’s School of Chemistry and Physics. Thus, “Removing CO₂ from the flue gas mixture is the focus of a lot of research.”

The material is a new type of metal-organic framework (MOF) material - a cluster of metal atoms connected by organic molecules. MOFs are known for their exceptional ability to store or separate gases such as CO₂, and the new type is no exception, said to show “exceptionally selective separation for CO₂ over N₂ (nitrogen)”, according to the researchers. Nitrogen is the other significant component of the waste gas released by coal-fired power stations.

“It is like a sponge but at a nanoscale,” said Associate Professor Sumby. “The material has small pores that gas molecules can fit into - a CO₂ molecule fits but a nitrogen molecule is slightly too big. That’s how we separate them.”

Separating CO₂ from nitrogen means it can be stored as opposed to being released into the atmosphere. The researchers said the MOF’s high separation performance “is associated with a moderate adsorption enthalpy and therefore an expected low energy cost for regeneration (removing the CO₂ for MOF re-use)”. This is opposed to other separation methods, which are energy-intensive and expensive.

Associate Professor Sumby said there are still further improvements which could be made, with “smarter ways to implement the benefits”. He says the researchers’ next step is “taking the material in powder form and dispersing it in a membrane”, which “may be more practical for industrial use”.

The project is funded by the Science Industry Endowment Fund and is a collaboration between researchers in the Centre of Advanced Nanomaterials, the School of Chemistry and Physics and CSIRO.