Post-combustion emission controls

Selective catalytic reduction of NO_x emissions from a 5.9 liter diesel engine using ethanol as a reductant

Authors
M.D. Kass, J.F. Thomas, S.A. Lewis, Sr., J.M. Storey, N. Domingo, R.L. Graves, A. Panov

Publication
SAE Paper 2003-01-3244, Society of Automotive Engineers, 2003

Abstract
NO_x emissions from a heavy-duty diesel engine were reduced by more than 90% and 80% utilizing a full-scale ethanol-SCR system for space velocities of 21000/h and 57000/h respectively. These results were achieved for catalyst temperatures between 360 and 400 degrees C and for C1:NO_x ratios of 4-6. The SCR process appears to rapidly convert ethanol to acetaldehyde, which slipped past the catalyst at appreciable levels at a space velocity of 57000/h. Ammonia and N₂O were produced during conversion; the concentrations of each were higher for the low space velocity condition. However, the concentration of N₂O did not exceed 10 ppm. NO_x reduction appeared to be enhanced by initial catalyst aging, with the presumed mechanism being sulfate accumulation within the catalyst. A concept for utilizing ethanol distilled from an E-diesel fuel as the SCR reductant was demonstrated.