Author/Authors :
Prestipino، نويسنده , , C and Berlier، نويسنده , , G and Llabrés i Xamena، نويسنده , , F.X and Spoto، نويسنده , , G and Bordiga، نويسنده , , S and Zecchina، نويسنده , , A and Turnes Palomino، نويسنده , , G and Yamamoto، نويسنده , , T and Lamberti، نويسنده , , C، نويسنده ,
Abstract :
We report an in situ IR, EPR, and high resolution XANES study on the Cu+(NO) and Cu+(NO)2 complexes formed at 80 K in Cu+–ZSM-5. Bare Cu2+ ions (<1%) exhibit an axial EPR spectrum, while bare Cu+ ions exhibit well resolved 1s→4pxy and 1s→4pz transitions (pxy/pz splitting of 3.1 eV), reflecting the same local symmetry. Cu+(NO) complex exhibits an anisotropic EPR signal, while XANES spectrum of dinitrosyl adducts presents three resolved components ascribed to the 1s→4px, 1s→4py, and 1s→4pz transitions (px/py and py/pz splitting of 3.8 and 2.6 eV, respectively) testifying the rupture of the axial symmetry of Cu+ bare cations upon NO adsorption. Upon increasing the temperature to 300 K, NO oxidizes a fraction of 75–85% of the cuprous ions.
