Cu-I sites in Cu(I)ZSM-5: A XAFS, IR and computer graphics study

IR and XAFS have been employed to investigate the local environment of Cu-I in Cu-I-ZSM-5 prepared by gas phase reaction of H-ZSM-5 with CuCl. Both XAFS and IR measurements show that copper species are momodispersed Cu-I ions occupying highly unsaturated sites easily accessible to small ligand molecules. Cu-I-ZSM-5 prepared in this way represent a model solid for investigating the structure of isolated Cu-I sites in zeolites. EXAFS analysis reveal that, in vacuum conditions, Cu-I cations are surrounded by 2.5 +/- 0.3 oxygens at 2.00 +/- 0.02 Angstrom. The combined use of EXAFS, IR and computer graphic simulations allows to infer that Cu-I ions in Cu-I -ZSM-5 are located in two families of sites.