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The Effects of CO, H2, and C3H6 on the SCR Reactions of an Fe Zeolite SCR Catalyst University of Michigan
- Format:
- Conference/Event
- Author/Creator:
- Smith, Smith, author.
- Conference Name:
- SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)
- Language:
- English
- Physical Description:
- 1 online resource
- Place of Publication:
- Warrendale, PA SAE International 2013
- Summary:
- Selective Catalytic Reduction (SCR) catalysts used in LeanNOx Trap (LNT) - SCR exhaust aftertreatment systemstypically encounter alternating oxidizing and reducingenvironments. Reducing conditions occur when diesel fuel isinjected upstream of a reformer catalyst, generating highconcentrations of hydrogen (H₂), carbon monoxide (CO), andhydrocarbons to deNOx the LNT. In this study, thefunctionality of an iron (Fe) zeolite SCR catalyst is explored witha bench top reactor during steady-state and cyclic transient SCRoperation.Experiments to characterize the effect of an LNTdeNOx event on SCR operation show that adding H₂ or COonly slightly changes SCR behavior with the primary contributionbeing an enhancement of nitrogen dioxide (NO₂) decomposition intonitric oxide (NO). Exposure of the catalyst to C₃H₆ (a surrogatefor an actual exhaust HC mixture) leads to a significant decreasein NOx reduction capabilities of the catalyst. Adegradation mechanism is proposed to account for the decrease inNOx conversion efficiency, highlighted by reactionsbetween NO₂ and C₃H₆ to make NO at a rate of similar order ofmagnitude as the Fast SCR reaction. This inhibits SCR reactionswhen the NO:NOx ratio favors NO, but can increaseNOx conversion when the NO:NOx ratio favorsNO₂.Ammonia (NH₃) storage is only marginally affected by thepresence of H₂, CO, or C₃H₆; but significant amounts of C₃H₆ can bestored on the catalyst. Further observation reveals that theoxidation effects of C₃H₆ are non-negligible and C₃H₆ stronglyinfluences the oxidation of NH₃. The degradation mechanism includesseven proposed reactions to model the experimental results ofadding H₂, CO, and C₃H₆ to the SCR feed gas during steady-state andtransient operation
- Notes:
- Vendor supplied data
- Publisher Number:
- 2013-01-1062
- Access Restriction:
- Restricted for use by site license
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