The adsorption of NO and NO 2 and their subsequent reduction by hydrazine monohydrate (HDM) over Fe-BEA zeolite were investigated using an FT-IR spectrophotometer equipped with an in-situ cell. Although NO and NO 2 molecules were adsorbed on Fe species in an unaltered state, some of them reacted with oxygen atoms, resulting in the adsorption of NO 2 and NO 3 − , respectively. The reducing species that had originated from HDM on Fe-BEA selectively reduced these molecules to N 2 , while a small amount of N 2 O was formed in the reduction of NO by HDM. NO and NO 2 were rapidly reduced by HDM through their adsorbed state even at 150 o C, and Fe species were required for their adsorption and for the formation of reducing species from HDM.
The deactivation of a barium oxide-based NO x storage and reduction (NSR) catalyst with hydrothermal treatment was studied by treating it with 10 vol% water vapor diluted in nitrogen at 850 o C. XRD, XPS, SEM, IR of CO adsorption, and the N 2 adsorption was used to investigate the physical and chemical changes of the NSR catalyst caused by the hydrothermal treatment. The 12 h hydrothermal treatment decreased its NO 2 storage capacity by 20%. However, the hydrothermal treatment significantly decreased its ability to reduce the stored NO 2 . The formation of an inactive phase consisting of platinum and aluminum is believed to be the cause of the severe deactivation of the NSR catalyst.
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