miércoles, 11 de febrero de 2009

New materials can selectively capture CO2, scientists say

Scientists have created metal-organic crystals capable of soaking up carbon dioxide gas like a sponge, which could be used to keep industrial emissions of the gas out of the atmosphere.
Chemists at the University of California Los Angeles said the crystals — which go by the name zeolitic imidazolate frameworks, or ZIFs — can be tailored to absorb and trap specific molecules.

An optical photograph of crystals of zeolitic imidazolate frameworks (ZIFs). The porous materials can be designed to soak up specific molecules, such as carbon dioxide, making them potentially useful to trap the greenhouse gas. (Omar Y. Yaghi/Science).

"The technical challenge of selectively removing carbon dioxide has been overcome," said UCLA chemistry professor Omar Yaghi in a statement.
"Now we have structures that can be tailored precisely to capture carbon dioxide and store it like a reservoir, as we have demonstrated. No carbon dioxide escapes. Nothing escapes — unless you want it to do so. We believe this to be a turning point in capturing carbon dioxide before it reaches the atmosphere."
Yaghi and his colleagues describe their findings in the Friday issue of the journal Science.
Little energy needed to create crystals
He said the crystals are non-toxic and would require little extra energy from a power plant, making them an ideal alternative to current methods of CO2 filtering. The porous structures can be heated to high temperatures without decomposing and can be boiled in water or solvents for a week and remain stable, making them suitable for use in hot, energy-producing environments like power plants.
The team of scientists created 25 ZIF crystal structures in a laboratory, three of which showed a particular affinity for capturing carbon dioxide. The highly porous crystals also had what the researchers called "extraordinary capacity for storing CO2": one litre of the crystals could store about 83 litres of CO2.
The researchers created all 25 crystals by combining their raw materials in thousands of chemical reactions, which they say is similar to the high-throughput methods used in pharmaceutical research.
As concern over climate change grows and its link to human-made carbon dioxide emissions becomes clearer, governments and businesses around the world are investigating carbon-capturing technologies.
Past estimates from United Nation's energy and climate experts have pegged the cost of capturing CO2 between $25 US and $60 US a tonne for conventional coal-fired plants.
Earlier this month, a task force established by the Alberta and federal governments issued a report calling for $2-billion to get five new carbon capture and storage facilities operating by 2015.

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