Real-time infrared detection of cyanide flip on silver-alumina NOx removal catalyst.

Spectroscopic studies of the mechanistic steps that occur on supported precious metal catalysts used in industrial and automotive applications are hampered by a dearth of suitable experimental methods. We used femtosecond laser excitation followed by nanosecond time-resolved in situ Fourier-transform infrared spectroscopy to initiate a catalytic reaction on alumina-supported silver catalysts, which are of interest in minimizing nitrogen oxide emissions from fuel-efficient lean-burn engines. We found that the key intermediate step in the reaction between carbon monoxide and nitric oxide is the flip of a cyanide group from a silver nanoparticle to the alumina support (with a lifetime of 2 microseconds), which indicates the central role played by the interface between the metal particle and the oxide support.