Low Temperature Soot Oxidation Via
The Melting Process Of Alkaline Salts
Author(s)
D. Hirabayashi, H. Hashikawa & K. Suzuki
Abstract
We investigated low temperature soot oxidation mechanisms using several kinds
of alkaline salts (LiCO3, LiCl, LiNO3, K2CO3, KCl, KNO3, Na2CO3, NaCl and
NaNO3). Soot oxidation activity was evaluated by CO, CO2 formation rate
during combustion of a simulated soot through a temperature programmed
oxidation experiments under simulated air conditions (O2 concentration = 10
vol%, total gas flow rate = 200 ml min-1, soot = 20mg, γ-alumina powder = 340
mg) by using an FID-GC with methanizer. In the case of soot oxidation without
molten salts, the TPO profile showed a single peak for CO, CO2 formation
around 770 K. On the other hand, in the case with nitrate-based alkaline salts
(LiNO3, KNO3 and NaNO3; 100 mg), a single or a multiple peak consisting of
two independent tops were observed in the lower temperature range (450-750
K). Visible observation using an optical microscope revealed the characteristic
mechanisms with some liquid phase contributions by melting and fluidization of
alkaline salts. These processes could enhance the soot oxidation in low
temperature ranges. Findings also proposed that the direct reaction between
carbon and nitrate-based alkaline salts which involved into oxidation
mechanisms at 450-650 K.
Keywords: soot oxidation, alkaline salts, oxidation mechanism.
1 Introduction
Soot particles emitted from diesel engines cause increasing attention due to their
probable negative impact on the human respiratory system. Therefore, during the
past decade, intensified techniques and methods have been made to reduce soot
emissions. It is unlikely that it will be possible to meet future particle emission
standards without the use of aftertreatment devices such as the diesel particulate
Keywords
soot oxidation, alkaline salts, oxidation mechanism.
Related Book
Other papers in this volume
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