MADISON -- In the world, there are a lot of small molecules people would like to get rid of, or at least convert to something useful, according to University of Wisconsin-Madison chemist Robert J. Hamers.
Think carbon dioxide, the greenhouse gas most responsible for far-reaching effects on global climate. Nitrogen is another ubiquitous small-molecule gas that can be transformed into the valuable agricultural fertilizer ammonia. Plants perform the chemical reduction of atmospheric nitrogen to ammonia as a matter of course, but for humans to do that in an industrial setting, a necessity for modern agriculture, requires subjecting nitrogen to massive amounts of energy under high pressure.
"The current process for reducing nitrogen to ammonia is done under extreme conditions," explains Hamers, a UW-Madison professor of chemistry. "There is an enormous barrier you have to overcome to get your final product."
Breaching that barrier more efficiently and reducing the huge amounts of energy used to convert nitrogen to ammonia by some estimates 10 percent of the world's electrical output has been a grail for the agricultural chemical industry. Now, that goal may be on the horizon, thanks to a technique devised by Hamers and his colleagues and published today (June 30, 2013) in the journal Nature Methods.
Like many chemical reactions, reducing nitrogen to ammonia is a product of catalysis, where the catalytic agent used in the traditional energy-intensive reduction process is iron. The iron, combined with high temperature and high pressure, accelerates the reaction rate for converting nitrogen to ammonia by lowering the activation barrier that otherwise keeps nitrogen, one of the most ubiquitous gases on the planet, intact.
"The nitrogen molecule is one of the happiest molecules around," notes Hamers. "It is incredibly stable. It doesn't do anything."
One of the big obstacles, according to Hamers, is that nitr
|Contact: Robert J. Hamers|
University of Wisconsin-Madison