Disproportionation of associated Cu2+ sites in Cu-ZSM-5 to Cu+ and Cu3+ and FTIR detection of Cu3+(NO) x (x =1, 2) species.

Highlights: [•] Adsorption of NO on Cu-ZSM-5 causes disproportionation of Cu2+ to Cu+ and Cu3+ ions. [•] The process occurs with participation of associated [Cu–O–Cu]2+ sites even at 100K. [•] The Cu3+ ions form two kinds of mononitrosyl species (1960 and 1947cm−1). [•] The Cu3+–NO species can accept a second NO molecule thus forming dinitrosyls. [•] At ambient temperature, Cu3+ ions are reduced by NO to Cu+ and Cu2+. [ABSTRACT FROM AUTHOR]