NH₃ cleanup on gold catalyst

Cleaning up ammonia in industrial waste gas streams by converting the compound to nitrogen and water could be an effective method for treating oxygen-containing waste gas, if a suitable catalyst were found. Some transition metals, such as platinum and iridium, can facilitate the conversion, but those catalysts produce unwanted side products including nitric oxide and nitrous oxide. Now, University of Texas, Austin, chemical engineers Jinlong Gong, C. Buddie Mullins, and coworkers have found that gold can do the job effectively. Specifically, the group reports that a model catalytic system, a gold single crystal pretreated with atomic oxygen, promotes catalytic oxidation of ammonia to nitrogen and water selectively (J. Am. Chem. Soc., published online June 27, dx.doi.org/10.1021/ja062624w). The researchers note that by-products can be eliminated by tuning the concentration of adsorbed oxygen atoms. They propose that ammonia decomposition proceeds by way of hydrogen abstraction from surface-bound ammonia.