Catalytic filters for the simultaneous removal of soot and NOx: Effect of CO2 and steam on the exhaust gas of diesel engines

GÁLVEZ, M.; ASCASO, S.; SUELVES, I.; MOLINER, R.; JIMÉNEZ, R.; GARCÍA, X.; GORDON, A.; LÁZARO, M.J.
Catalysis Today 176:1 (2011) 134-138.

DOI: 10.1016/j.cattod.2011.01.030

Abstract

Catalytic filters for the simultaneous removal of soot and nitrogen oxides were prepared by means of coating cordierite monoliths with alumina-based suspensions containing Cu, Co or V and K as the catalytically active phase. Textural and chemical properties of the coated monoliths were determined by means of N₂-physisorption, XRD, SEM-EDX and temperature programmed reduction. Activity of the catalytic filters in the simultaneous removal of soot and nitrogen oxides was tested in a fixed bed installation in absence and in presence of steam and CO₂. Complete soot oxidation was measured for some of the assayed catalytic filters, with high selectivity to CO₂ formation. NO reduction was preceded by a peak of NO₂ formation, which corresponded to maximum soot oxidation rate, pointing to the formation of NO₂ as a key step in the reaction mechanism for the simultaneous removal. Presence of steam and CO₂ diminished catalytic activity and selectivity for soot oxidation.