In situ diffuse reflectance infrared Fourier transform spectroscopy study of surface species involved in NO(χ) reduction by ethanol over alumina-supported silver catalyst

In situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been used to investigate the surface species involved in NO(x) reduction by ethanol over alumina-supported silver catalyst. The experiments were carried out in dynamic conditions (under reaction mixture flow and reaction temperature) at atmospheric pressure. The DRIFT measurements were combined with gas chromatography (GC) analysis to monitor the N₂ formation under reaction mixture and when the reaction mixture flow was switched to He followed by heating the catalyst under He flow (mixture, 250°C→He, 250°C→ heating under He). A parallelism has been observed between the isocyanate band change and N₂ formation during the step change experiment using an initial C₂H₅OH/NO/O₂/He reaction mixture. Furthermore, the isocyanate species (NCO) were found to be generated from the decomposition of adsorbed organic nitro compounds formed under both ethanol/NO/O₂/He and ethanol/NO/He and reaction mixtures. The role of oxygen in NO(x) reduction process was determined by comparing the result of different step-change experiment rising an initial reaction mixture containing oxygen and without oxygen.