The geometries and harmonic vibrational frequencies of several possible intermediates involved in the NO decomposition mechanism catalyzed by Cu-ZSM5: ZCu(NO2)(NO), ZCu(N2O3), ZCu(N2O)(O2), ZCu(N2O), and ZCu(O2), have been determined using the B3LYP density functional approach and a tritetrahedral model for the zeolite. Results show that, although ZCu(NO2)(NO) and ZCu(N2O3) species are very stable with respect to the ground state ZCuO + 2NO asymptote, the NO decomposition is not expected to proceed through these intermediates. At high temperatures, formation of ZCu(O2) may occur from ZCuO + 2NO through a ZCu(OONNO) like transition state in the triplet surface. This pathway may compete with the one previously reported for the O-transfer to ZCuO from N2O and, thus, should be considered to understand the observed reactivity.
|Journal||Journal of Physical Chemistry B|
|Publication status||Published - 14 Feb 2002|