Fast-regenerable sulfur dioxide absorbents for lean-burn diesel engine emission control
It is known that sulfur oxides contribute significantly and deleteriously to the overall performance of lean-burn diesel engine aftertreatment systems, especially in the case of NOx traps. A Ag-based, fast regenerable SO2 absorbent has been developed and will be described. Over a temperature range of 300oC to 550oC, it absorbs almost all of the SO2 in the simulated exhaust gases during the lean cycles and can be fully regenerated by the short rich cycles at the same temperature. Its composition has been optimized as 1 wt% Pt-5wt%Ag-SiO2, and the preferred silica source for the supporting material has been identified as inert Cabosil fumed silica. The thermal instability of Ag2O under fuel-lean conditions at 230oC and above makes it possible to fast regenerate the sulfur-loaded absorbent during the following fuel-rich cycles. Pt catalyst helps reducing Ag2SO4 during rich cycles at low temperatures. And the chemically inert fumed SiO2 support gives the absorbent long term stability. This absorbent shows great potential to work under the same lean-rich cycling conditions as those imposed on the NOx traps, and thus, can protect the downstream particulate filter and the NOx trap from sulfur poisoning.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1000595
- Report Number(s):
- PNNL-SA-70465; 5395; VT0403000; TRN: US201101%%399
- Journal Information:
- Applied Catalysis. B, Environmental, 100(1-2):238-244, Vol. 100, Issue 1-2; ISSN 0926-3373
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORBENTS
CATALYSTS
DIESEL ENGINES
EXHAUST GASES
INSTABILITY
PARTICULATES
PERFORMANCE
POISONING
SILICA
STABILITY
SULFUR
SULFUR DIOXIDE
SULFUR OXIDES
SOx trap
regenerable
lean-burn engine
emission control
Ag
lean-rich cycle
NOx trap
NOx reduction
Environmental Molecular Sciences Laboratory