Dc. Sayle et al., ACTIVE-SITE CONFIGURATIONS WITHIN THE NO DECOMPOSITION CATALYST, CU-ZSM-5 - THE ROLE OF FRAMEWORK ALUMINUM, Journal of materials chemistry, 7(8), 1997, pp. 1635-1639
Computer modelling techniques have been used to identify the extra-fra
mework copper clusters which form the active sites in the Cu-ZSM-5 de-
NOx catalysts. In particular, we suggest that both isolated copper and
Cu-OH-Cu species represent useful models for the active site. These s
pecies are strongly anchored to the zeolite wall via framework alumini
um, in the absence of which the clusters undergo significant structura
l modifications. Specifically, we observe changes both in the Cu-O and
Cu-Cu bond distances and also in the coordination numbers of the copp
er. We suggest that such changes are responsible, in part, for the rel
ationship between the copper loading and Si/Al ratio and the catalytic
activity of the material.