XAFS study on active Pr sites in zeolite as a photocatalyst for decomposition of nitrous oxide

The praseodymium-exchanged mordenite degassed at 873 K acted as a highly active heterogeneous photocatalyst for the stoichiometric decomposition of N₂O. Analysis of Pr L₃-edge EXAFS revealed that the Pr species were isolated each other in the large channel of zeolite, and that the active Pr species were coordinated by ca. four oxygen atoms and one Al atom. On the other hands, the inactive Pr species are surrounded by ca. 10 oxygens of adsorbed waters. The former low-coordinated Pr species allowed a strong adsorption of N₂O, which could be the first step of the decomposition reaction.