11 Nov Chemists discover new way to harness energy from ammonia
A research team at the University of Wisconsin–Madison has identified a new way to convert ammonia to nitrogen gas through a process that could be a step toward ammonia replacing carbon-based fuels.
The discovery of this technique, which uses a metal catalyst and releases, rather than requires, energy, was reported Nov. 8 in Nature Chemistry and has received a provisional patent from the Wisconsin Alumni Research Foundation.
“The world currently runs on a carbon fuel economy,” explains Christian Wallen, an author of the paper and a former postdoctoral researcher in the lab of UW–Madison chemist John Berry. “It’s not a great economy because we burn hydrocarbons, which release carbon dioxide into the atmosphere. We don’t have a way to close the loop for a true carbon cycle, where we could transform carbon dioxide back into a useful fuel.”
To move toward the United Nations’ goal for the world to become carbon-neutral by 2050, scientists must consider environmentally responsible ways to create energy from elements other than carbon, and the UW–Madison team is proposing a nitrogen energy economy based on interconversions of nitrogen and ammonia.
The scientists were excited to find that the addition of ammonia to a metal catalyst containing the platinum-like element ruthenium spontaneously produced nitrogen, which means that no added energy was required. Instead, this process can be harnessed to produce electricity, with protons and nitrogen gas as byproducts. In addition, the metal complex can be recycled through exposure to oxygen and used repeatedly, all a much cleaner process than using carbon-based fuels.
“We figured out that, not only are we making nitrogen, we are making it under conditions that are completely unprecedented,” says Berry, who is the Lester McNall Professor of Chemistry and focuses his research efforts on transition metal chemistry. “To be able to complete the ammonia-to-nitrogen reaction under ambient conditions — and get energy — is a pretty big deal.”