title: NO2 adsorption on BaO/Al2O3: the nature of nitrate species.
abstract: Temperature programmed desorption, infrared spectroscopy, and (15)N solid state NMR spectroscopy were used to characterize the nature of the nitrate species formed on Al(2)O(3) and BaO/Al(2)O(3) NO(x) storage/reduction materials. Two distinctly different nitrate species were found: surface nitrates that are associated with a monolayer BaO on the alumina support, and a bulk-like nitrate that forms on this thin BaO layer. The surface nitrates desorb as NO(2) at lower temperatures than do the bulk-like nitrates, which decompose as NO+O(2) at higher temperatures. The amount of NO(x) stored in the monolayer nitrate is proportional to the surface area of the catalyst, while that in the bulk nitrate increases with BaO coverage.
authors.forename: Janós
authors.initials: J
authors.lastname: Szanyi
authors.forename: Ja Hun
authors.initials: JH
authors.lastname: Kwak
authors.forename: Do Heui
authors.initials: DH
authors.lastname: Kim
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Burton
authors.forename: Charles H F
authors.initials: CH
authors.lastname: Peden
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D017609:Barium Compounds / Q000737:chemistry*; D002384:Catalysis; D009566:Nitrates / Q000737:chemistry*; D009585:Nitrogen Dioxide / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013696:Temperature
chemical_list: D017609:Barium Compounds; D009566:Nitrates; D010087:Oxides; C077606:barium oxide; D000537:Aluminum Oxide; D009585:Nitrogen Dioxide