Authors
V.K. Chakravarthy, C.S. Daw, K.E. Lenox
Publication
SAE
Paper 2003-01-3246, Society of Automotive Engineers, 2003
Abstract
We study
the NOx storage process in lean NOx traps (LNTs)
using bench-flow experiments and simulated diesel exhaust. Given that
formulation alone is an inadequate indicator of performance (due to the
effects of manufacturing processes) a minimal set of experiments is
always needed to compare the performance of LNTs. We define simple
performance measures based on such a set of experiments that can be used
to compare lean phase operations of various LNTs under various
conditions concisely. Though the noble metal sites are essential for
storage, the benefits of increasing noble metal loading start to wane
beyond a certain limit. Our experiments suggest a possibility that a
lean NOx reduction reaction may be occuring in LNTs. If this
reaction is confirmed further in future experiments, its products need
to be identified. The sorbent shifts the equilibrium between NO and
NO2 towards NO. We propose an experimental protocol for
generating the adsorption isotherm for NOx storage from
equilibrium capacity measurements that can be used for verifying kinetic
mechanisms and for developing simulation models.
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