Combined IR spectroscopy and kinetic modeling of NO storage and NO-oxidation on Fe-BEA SCR catalysts

A multi-site kinetic model for NOx adsorption/desorption and NO to NO2 oxidation on Fe-BEA was developed, based on in-situ IR spectroscopic measurements. NO and NO2 adsorption, along with NO/O-2 co-adsorption were initially investigated on H- and Fe-BEA lab-synthesized samples, in order to elucidate the contribution of acidic and iron sites. Simultaneously an in-situ IR spectroscopic study allowed to characterize a variety of NOx adspecies, including iron nitrosyls, nitrosium anions, nitrites as well as aluminum and iron based nitrates. Based on recorded spectral features a multi-site kinetic model for NOx storage and NO oxidation was developed, accounting for interactions of nitrogen oxides with different surface sites. The model was finally validated, through simulation of various experimental conditions, depicting satisfactorily mechanistic aspects related to NOx storage and NO oxidation on acidic and metallic sites. (C) 2013 Elsevier B.V. All rights reserved.