The 2-way diesel particulate filter/selective catalytic
reduction
(DPF/SCR) emission reduction system has been considered as a potential
candidate for future emission standards owing to its advantages in
cost savings and packaging flexibility. For the 2-way device, Cu–zeolite
is coated inside the DPF substrate as nitrogen oxide (NO
x
) reducing (DeNO
x
) catalytic
material. Therefore, when exhaust gas passes through the 2-way device,
NO
x
reduction and soot filtration occur
simultaneously. However, the operating characteristics of the combinatorial
device might be different from individual DPF and SCR devices. In
this work, a previously developed model was improved to include soot
filtration and oxidation. The model has been tested and validated
with experimental data from a reactor flow bench in a systematic manner
and applied to capture the effect of soot deposits on NO
x
reduction performance in a 2-way DPF/SCR device.
Accordingly, the soot oxidation characteristics of a 2-way device
are investigated with various feed gas compositions. Then the effect
of soot deposit on the SCR reaction is investigated in terms of deterioration
of DeNO
x
performance and the interaction
between soot oxidation reactions and DeNO
x
SCR reactions.
The two-way diesel particulate filter (DPF)/selective catalytic reduction (SCR) emissions-reduction system has recently been extensively studied due to its potential cost savings and packing flexibility. Unlike a conventional emissions-reduction system that consists of a DPF and an SCR for reduction of both particulate matter and nitrogen oxides (NO x ), this twoway system incorporates SCR function into a wall-flow DPF as a single device by coating SCR catalysts into the filter wall of the DPF. Such a combinatorial system has the advantage of lower system volume and cost, since exhaust gas undergoes soot filtering and NO x reduction reaction simultaneously as it passes through the channels and filter wall. In this work, the mathematical formulations which govern the physical and chemical phenomena in the twoway DPF/SCR are derived and a computer simulation model is developed based on these formulations. The model has been validated and tested with experimental data from a reactor flow bench in a systematic manner, which captures ammonia adsorption/desorption and NO x reduction of the blended two-way DPF/SCR device.
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