Lean NO sub(x) catalysis for diesel passenger cars: investigating effects of sulfur dioxide and space velocity

Effects of sulfur dioxide (SO sub(2)) and space velocity (SV) have been investigated as part of a strategy to optimize NO sub(x) removal with lean NO sub(x) catalysts. Elimination of feedgas SO sub(2) can lower NO sub(x) light off temperature for both Pt and Cu zeolite. Some Pt catalysts do not show...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Environmental, 1996-01, Vol.10 (1-3), p.157-181
Main Authors: Adams, Karen M, Cavataio, John V, Hammerle, Robert H
Format: Article
Language:English
Subjects:
Nitrogen oxides
Q1
Sulfur
Sulfur dioxide
Velocity
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Summary:Effects of sulfur dioxide (SO sub(2)) and space velocity (SV) have been investigated as part of a strategy to optimize NO sub(x) removal with lean NO sub(x) catalysts. Elimination of feedgas SO sub(2) can lower NO sub(x) light off temperature for both Pt and Cu zeolite. Some Pt catalysts do not show this behavior. Additional evaluation of a Cu zeolite catalyst demonstrates that poisoning by feedgas SO sub(2) is reversible during evaluation or aging. This result suggests that if sulfur could be removed from diesel fuel, aged Cu zeolite catalysts could be practical. Decreasing space velocity will help NO sub(x) removal over Pt by (i) lowering NO sub(x) light off temperature, (ii) lowering the temperature at which peak NO sub(x) conversion occurs, (iii) increasing the level of peak NO sub(x) conversion, and (iv) widening the temperature window for NO sub(x) reduction. For Cu zeolite, decreasing space velocity can help mainly by lowering NO sub(x) light off temperature and temperature where maximum NO sub(x) conversion starts. Both increased catalyst volume and sulfur removal provide Pt catalysts with a NO sub(x) temperature window that coincides better with low temperatures where most NO sub(x) mass is emitted. SV effects on lean NO sub(x) reduction are explained by discussion of possible mechanistic features.
ISSN:0926-3373