INCAPE   05401
INSTITUTO DE INVESTIGACIONES EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Unidad Ejecutora - UE
artículos
Título:
Activity and stability of BaKCo/CeO2 catalysts for diesel soot oxidation
Autor/es:
M. A. PERALTA; M. S. ZANUTTINI; C. A. QUERINI
Revista:
APPLIED CATALYSIS B-ENVIRONMENTAL
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2011 vol. 110 p. 90 - 98
ISSN:
0926-3373
Resumen:
The activity and stability of Ba,K,Co/CeO2 catalyst in the diesel soot oxidation
reaction is studied. Different modes of preparation are analyzed, varying both the cobalt
precursor and its order of impregnation. In order to study the stability in a diesel exhaust
atmosphere, the catalysts were pretreated in streams of CO2, H2O, NO and SO2. The
fresh and the treated catalysts were characterized by FTIR and XRD techniques. The
catalytic activity was measured by TPO of soot-catalyst mixtures. The tight contact was
used to analyse the intrinsic activity. It was found that the activity was higher for the
catalysts prepared using Co(NO3)2 compared with the catalysts prepared using
Co(AcO)2. This is because in the former, KNO3 is present on the catalyst, being this
compound very active for this reaction. The thermal stability is lower for the catalyst
prepared with Co(NO3)2. This catalyst displays a higher K lost when treated at high
temperature. When K is present as K2CO3, as is the case of the catalysts prepared with
Co(AcO)2, the thermal stability is higher since K2CO3 is less volatile than KNO3. All
the catalysts are stable in the presence of mixtures of (CO2 + H2O + NO + O2) having a
composition similar to a real diesel exhaust. Under these conditions, the K mantains its
original chemical state, either carbonate or nitrate, depending on the precursor used in
the catalyst preparation. In presence of SO2, all the catalysts deactivate due to K2SO4
formation, which is not active for soot combustion. However, the sensitivity to SO2
depends on the precursors used to prepare the catalyst. The Ba,K,Co/CeO2 catalyst
prepared impregnating Co(NO3)2 on the Ba,K/CeO2 catalyst has a higher resistance to
the deactivation by SO2, since the following reaction occurs: Ba(NO3)2 + K2SO4
BaSO4 + KNO3, which implies that active KNO3 will dissapear slower from the
catalytic surface, thus maintaining the activity. TPO experiments of the catalyst in loose
contact with soot were also carried out. The Ba,K,Co/CeO2 catalyst prepared
impregnating Co(NO3)2 on the Ba,K/CeO2 catalyst showed the higher activity in loose
contact mode.