title: Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios.
abstract: Cu-SSZ-13 has been characterized by different spectroscopic techniques and compared with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios and prepared by the same ion exchange procedure. On vacuum activated samples, low temperature FTIR spectroscopy allowed us to appreciate a high concentration of reduced copper centres, i.e. isolated Cu(+) ions located in different environments, able to form Cu(+)(N2), Cu(+)(CO)n (n = 1, 2, 3), and Cu(+)(NO)n (n = 1, 2) upon interaction with N2, CO and NO probe molecules, respectively. Low temperature FTIR, DRUV-Vis and EPR analysis on O2 activated samples revealed the presence of different Cu(2+) species. New data and discussion are devoted to (i) [Cu-OH](+) species likely balanced by one framework Al atom; (ii) mono(μ-oxo)dicopper [Cu2(μ-O)](2+) dimers observed in Cu-ZSM-5 and Cu-β, but not in Cu-SSZ-13. UV-Vis-NIR spectra of O2 activated samples reveal an intense and finely structured d-d quadruplet, unique to Cu-SSZ-13, which is persistent under SCR conditions. This differs from the 22,700 cm(-1) band of the mono(μ-oxo)dicopper species of the O2 activated Cu-ZSM-5, which disappears under SCR conditions. The EPR signal intensity sets Cu-β apart from the others.
authors.affiliation: Department of Chemistry, NIS Centre of Excellence, University of Turin, Via Giuria 7, 10125 Torino, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Giordanino
authors.forename: Peter N R
authors.initials: PN
authors.lastname: Vennestrøm
authors.forename: Lars F
authors.initials: LF
authors.lastname: Lundegaard
authors.forename: Frederick N
authors.initials: FN
authors.lastname: Stappen
authors.forename: Susanne
authors.initials: S
authors.lastname: Mossin
authors.forename: Pablo
authors.initials: P
authors.lastname: Beato
authors.forename: Silvia
authors.initials: S
authors.lastname: Bordiga
authors.forename: Carlo
authors.initials: C
authors.lastname: Lamberti