Washington, March 9 : Researchers have developed a new, low-cost material for capturing carbon dioxide (CO2) from the smokestacks of coal-fired power plants and other generators of the greenhouse gas.
The new material, which is known as hyperbranched aluminosilica (HAS), has been developed by Christopher Jones, a professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology.
Existing CO2 capture techniques involve the use of solid materials that lack sufficient stability for repeated use - or liquid adsorbents that are expensive and require significant amounts of energy.
Produced with a simple one-step chemical process, the new material has a high capacity for absorbing carbon dioxide - and can be reused many times.
The material is also combined with improved heat management techniques, which helps to provide a cost-effective way to capture large quantities of carbon dioxide from coal-burning facilities.
"Our material has the combination of high capacity, easy synthesis, low cost and a robust ability to be recycled - all the key criteria for an adsorbent that would be used on an industrial scale," said Jones.
"This is something that you could imagine scaling up for commercial use," he added.
Growing concern over increased levels of atmospheric carbon dioxide has prompted new interest in techniques for removing the gas from the smokestacks of such large-scale sources as coal-fired electric power plants.
But to minimize their economic impact, the cost of adding such controls must be minimized so they don't raise the price of electricity significantly.
Working with Department of Energy scientists Daniel Fauth and McMahan Gray, Jones and graduate students Jason Hicks and Jeffrey Drese have developed a way to add CO2-adsorbing amine polymer groups to a solid silica substrate using covalent bonding.
The strong chemical bonds make the material robust enough to be reused many times.
"Given the volumes involved, you must be able to recycle the adsorbent material for the process to be cost-effective," said Jones. "Otherwise, you would be creating large and expensive waste streams of adsorbent," he added.
To test the effectiveness of their new material, the Georgia Tech researchers passed simulated flue gases through tubes containing a mixture of sand and HAS.
The CO2 was adsorbed at temperatures ranging from 50 to 75 degrees Celsius. Then the HAS was heated to between 100 and 120 degrees Celsius to drive off the gas so the adsorbent could be used again.
The researchers tested the material across 12 cycles of adsorption and desorption, and did not measure a significant loss of capacity.
The HAS material can adsorb up to 5 times as much carbon dioxide as some of the best existing reusable materials.