TY - JOUR
T1 - Promotion Effects in the Reduction of NO by CO over Zeolite-Supported Rh Catalysts
AU - Lepage, M.
AU - Visser, T.
AU - Soulimani, F.
AU - Iglesias-Juez, A.
AU - Weckhuysen, B.M.
PY - 2010
Y1 - 2010
N2 - Rh nanoparticles supported on a series of zeolite Y samples containing different monovalent (H+, Na+, Rb+,
and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations have been used as model systems to investigate
the effect of promoter elements in the reduction of NO by CO. Infrared (IR) spectroscopy with NO as a
probe molecule allowed monitoring of the electronic changes in the local environment of Rh. The IR bands
corresponding to linearly adsorbed NO, i.e., linear and dinitrosyl species, were found to shift to lower
wavenumbers with increasing ionic radius-to-charge ratio of the cation. Simultaneously, a lower ignition
temperature for NO reduction was observed. In addition, the relative intensity of the bridge-bonded NO band
as compared to the total absorbance of Rh-bonded NO species decreased with increasing Lewis acidity of the
cation, as expressed by the Kamlet-Taft parameter R. The latter observation matches with similar trends,
observed in a previous study (Lepage, M., et al., J. Phys. Chem. C 2008, 112, 9394) for the same catalysts
using CO as the IR probe molecule, which could be related to the Rh activity for the CO oxidation reaction.
The samples of the present study also showed different catalytic activities, although a straightforward correlation
between the results obtained with NO IR spectroscopy and the catalytic reduction of NO by CO could not be
established.
AB - Rh nanoparticles supported on a series of zeolite Y samples containing different monovalent (H+, Na+, Rb+,
and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations have been used as model systems to investigate
the effect of promoter elements in the reduction of NO by CO. Infrared (IR) spectroscopy with NO as a
probe molecule allowed monitoring of the electronic changes in the local environment of Rh. The IR bands
corresponding to linearly adsorbed NO, i.e., linear and dinitrosyl species, were found to shift to lower
wavenumbers with increasing ionic radius-to-charge ratio of the cation. Simultaneously, a lower ignition
temperature for NO reduction was observed. In addition, the relative intensity of the bridge-bonded NO band
as compared to the total absorbance of Rh-bonded NO species decreased with increasing Lewis acidity of the
cation, as expressed by the Kamlet-Taft parameter R. The latter observation matches with similar trends,
observed in a previous study (Lepage, M., et al., J. Phys. Chem. C 2008, 112, 9394) for the same catalysts
using CO as the IR probe molecule, which could be related to the Rh activity for the CO oxidation reaction.
The samples of the present study also showed different catalytic activities, although a straightforward correlation
between the results obtained with NO IR spectroscopy and the catalytic reduction of NO by CO could not be
established.
U2 - 10.1021/jp910371j
DO - 10.1021/jp910371j
M3 - Article
SN - 1932-7447
VL - 114
SP - 2282
EP - 2292
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
ER -