17 research outputs found
Coordination Environment of Copper Sites in Cu-CHA Zeolite Investigated by Electron Paramagnetic Resonance
A consistent reaction mechanism for the selective catalytic reduction of NO with NH<sub>3</sub>
Improved catalytic performance of hierarchical ZSM-5 synthesized by desilication with surfactants
Interaction of NH<sub>3</sub> with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study
In the typical NH<sub>3</sub>–SCR
temperature range (100–500
°C), ammonia is one of the main adsorbed species on acidic sites
of Cu-SSZ-13 catalyst. Therefore, the study of adsorbed ammonia at
high temperature is a key step for the understanding of its role in
the NH<sub>3</sub>–SCR catalytic cycle. We employed different
spectroscopic techniques to investigate the nature of the different
complexes occurring upon NH<sub>3</sub> interaction. In particular,
FTIR spectroscopy revealed the formation of different NH<sub>3</sub> species, that is, (i) NH<sub>3</sub> bonded to copper centers, (ii)
NH<sub>3</sub> bonded to Brønsted sites, and (iii) NH<sub>4</sub><sup>+</sup>·<i>n</i>NH<sub>3</sub> associations.
XANES and XES spectroscopy allowed us to get an insight into the geometry
and electronic structure of Cu centers upon NH<sub>3</sub> adsorption,
revealing for the first time in Cu-SSZ-13 the presence of linear Cu<sup>+</sup> species in O<sub>fw</sub>–Cu–NH<sub>3</sub> or H<sub>3</sub>N–Cu–NH<sub>3</sub> configuration