Material captures carbon

US researchers have developed a new material for capturing carbon dioxide (CO₂) from the chimneys of coal-fired power plants and other generators of the greenhouse gas. 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.

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.

'This is something that you could imagine scaling up for commercial use,' said Christopher Jones, a professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology. 'Our material has the combination of high capacity, easy synthesis, low cost and an ability to be recycled - all the key criteria for an adsorbent that would be used on an industrial scale.'

Details of the new material, known as hyperbranched aluminosilica (HAS), are scheduled to appear in the March 19 issue of the Journal of the American Chemical Society. The research was supported by the US Department of Energy’s National Energy Technology Laboratory.

Production of the HAS material is relatively simple, and requires only the mixing of a silica substrate with a precursor of an amine polymer in solution. The amine polymer is initiated on the silica surface, producing a solid material that can be filtered out and dried.

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 five times as much carbon dioxide as some of the best existing reusable materials.

The HAS material works in the presence of moisture, an unavoidable by-product of the combustion process.