Molecular car park: material packs in carbon dioxide.A crystalline material composed of metal and organic building blocks holds more carbon dioxide carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. than other porous substances do, chemists report. The discovery could lead to a device that reduces power plant emissions of this greenhouse gas greenhouse gas n. Any of the atmospheric gases that contribute to the greenhouse effect. greenhouse gas . About 40 percent of the carbon dioxide released in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. in 2003 came from electric power plants, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the Department of Energy. A potential strategy for reducing emissions is to fit plant flues with materials that capture the gas from exhaust. Metal-organic frameworks had previously stored hydrogen (SN: 6/14/03, p. 382). In the new study, Omar M. Yaghi and Andrew R. Millward of the University of Michigan (body, education) University of Michigan - A large cosmopolitan university in the Midwest USA. Over 50000 students are enrolled at the University of Michigan's three campuses. The students come from 50 states and over 100 foreign countries. in Ann Arbor measured the adsorption adsorption, adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see adhesion and cohesion). of carbon dioxide by nine different frameworks, each composed of organic compounds and either zinc or copper. The researchers exposed each framework to increasing amounts of carbon dioxide gas in a closed system at room temperature. A framework containing zinc swallowed the largest amount of carbon dioxide--33.5 millimoles of gas per gram of material, or 1.4 times its own weight. The structure has a surface area of 4.5 square kilometers per gram. The frameworks excel at containing carbon dioxide, says Yaghi, because they can "bring the gas molecules close to each other, like cars in a car park." The gas molecules repel one another, but the attraction between the gas molecules and the metal-organic framework is stronger than the repulsive force. So, in the pores of the material, the gas occupies a smaller volume then it would alone, Yaghi says. A container filled with the winning frame-work can take up nine times as much carbon dioxide as the empty container would and twice as much as a container filled with a carbon-based material previously tested for carbon dioxide storage. The researchers report these results in the Dec. 28, 2005 Journal of the American Chemical Society
The researchers are now working with engineers to scale up the technology and study its effectiveness in flues. They envision a power plant column housing tons of the framework. The material is reusable because in the absence of the high pressures found in the flue exhaust, the carbon dioxide freely leaves the material. Gas captured from the exhaust might be used to manufacture polymers or incorporated into other industrial materials, says Yaghi. "It's an interesting piece of work," says Mark Thomas of the University of Newcastle University of Newcastle can refer to:
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