Stability of K- La2O3 catalysts during the combustion of Diesel soot. High Frequency CO2 Pulses and soot - catalyst contacting studies.

M.L. PISARELLO; C. SAUX; E.E. MIRÓ; C.A.QUERINI

STUDIES IN SURFACE SCIENCE AND CATALYSIS

ELSEVIER

Lugar: Amsterdam; Año: 2001 vol. 139 p. 141 - 148

0167-2991

The catalytic behavior of K-La2O3 was studied for diesel soot combustion.  Thermal stability of these catalysts is very good, as measured by temperature-programmed-oxidation analyses. To evaluate the stability of the catalytic surface, pulses of CO2 every ten seconds were injected to the catalyst at high temperatures, e.g. 400°C and 500°C.  This technique proved to be very useful to verify the stability of the surface to thermal treatments.  Minor changes that were not detected by the activity test, were observed by modifications in the dynamics of the CO2 adsorption-desorption process. The soot-catalyst contacting phenomenon was also addressed.  A synergic La-K effect was observed, by which mechanical mixtures of soot with K-La2O3 showed higher combustion rates than those observed when K and La were directly deposited on soot surface.