XANES and EXAFS analysis of copper ion-exchanged ZSM-5 zeolite catalyst used for nitrogen monoxide decomposition

The Variety of Carbon-Metal Bonds inside Cu-ZSM-5 Zeolites: A Density Functional Theory Study

“…In this situation, configurations of the two copper cations within a ZSM-5 cavity may be responsible for the unsaturated hydrocarbon bindings, in addition to their copper coordination environment. Experimentally the presence of Cu pairs in ZSM-5 was demonstrated by using extended X-ray absorption fine structure (EXAFS) [61,62,63] spectroscopy and X-ray power diffraction [45] studies. To fully understand behaviors of an unsaturated hydrocarbon inside a ZSM-5 cavity, it is indispensable to clarify how configurations of the two copper cations inside ZSM-5 affect the properties of adsorbed unsaturated hydrocarbons.…”

Adsorption of benzothiophene on Y zeolites investigated by infrared spectroscopy and flow calorimetry

“…4 presents the DRIFT spectra recorded from the thermal desorption of benzothiophene adsorbed on the pre-treated CuY in the regions of O-H and C-H stretching vibrations. Compared to NiY, the Cu(II) species in CuY is much easier to auto-reduce to Cu(I) during pre-treatment in helium flow at 450 8C [31,32]. Depending on the pre-treatment conditions, the auto-reduction of the Cu(II) species will lead to the production of the hydroxyl groups and degradation of the zeolite pore structure.…”

Exchange and reduction of Cu2+ ions in clinoptilolite

“…If the loading exceeds 200% of the nominal exchange, the excess copper is certainly present as the oxide [34]. An EXAFS study [38] produced evidence for the Cu-O distances of 2.01 and 3.13 Å in Cu-ZSM-5, the latter occurring in the overexchanged zeolites and ascribed to CuO species. In any case, these processes, if continued, lead to formation of the precipitated phases mentioned earlier.…”