Rapid-Scan Operando Infrared Spectroscopy

Novel methodology, referred to as rapid-scan operando, has been demonstrated to be a highly powerful tool for studying reaction mechanisms in heterogeneous catalysis, because it combines rapid scan for IR monitoring in the milliseconds time frame and operando methodology. As proof of concept, the NO_x–CO and NO_x–H₂ reactions were studied as model catalyzed reactions with practical interest for removal of NO_x in diesel exhausts. Rapid-scan operando experiments confirmed state-of-the-art knowledge concerning the reaction mechanisms and, more importantly, allowed us to elucidate, for the first time, the different roles of the surface hydroxy groups depending on the reductant used (CO or H₂). Moreover, this new tool was used to distinguish the behavior of carbonates and nitrites under reaction conditions that could not be monitored by conventional IR spectroscopy approaches owing to overlap of their absorbance bands.