15/11/2021

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. 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 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.

Ammonia has been burned as a fuel source for many years. During World War II, it was used in automobiles, and scientists today are considering ways to burn it in engines as a replacement for gasoline, particularly in the maritime industry. However, burning ammonia releases toxic nitrogen oxide gases. The new reaction avoids those toxic byproducts. If the reaction were housed in a fuel cell where ammonia and ruthenium react at an electrode surface, it could cleanly produce electricity without the need for a catalytic converter.

Though some ammonia fuel cells already exist, they, unlike this new process, require added energy, for example, by first splitting ammonia into nitrogen and hydrogen. The group's next steps include figuring out how to engineer a fuel cell that takes advantage of the new discovery and considering environmentally friendly ways to create the needed starting materials.

https://phys.org/news/2021-11-chemists-harness-energy-ammonia.html

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