TY - JOUR
T1 - On-line determination of soot oxidation reactivity
AU - Rinkenburger, Alexander
AU - Niessner, Reinhard
AU - Haisch, Christoph
N1 - Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/6
Y1 - 2019/6
N2 - Soot particles in the atmosphere significantly affect human health as well as the climate. In order to avoid soot emissions, exhaust gases are filtered and the particles are trapped on a filter. The particles are eventually removed by catalytic oxidation to CO2, a process that requires elevated temperatures. The reactivity, i.e. the temperature required for this process, is currently determined after sample collection by techniques such as temperature-programmed oxidation (TPO), Raman microscopy or high-resolution transmission electron microscopy (HRTEM), which are all time-consuming and expensive. Furthermore, a significant amount of soot has to be collected prior to the analysis. This study aims for a straight-forward method to characterize the oxidation reactivity of exhaust soot on-line. A differential flow-through oven-system was built to thermally treat soot and determine the oxidation losses in comparison to a reference channel. The performance of the system was assessed by propane soot as well as by K2CO3-containing soot, which feature largely different reactivities in earlier studies. The results of the new system are compared to TPO measurements by using the same temperature program. K2CO3-containing soot shows oxidation at significantly lower temperatures than pure propane soot. Photoacoustic spectroscopy (PAS) revealed a considerable temperature-dependent decrease of soot mass concentrations, starting at lower temperatures for the K2CO3-containing soot. Beyond that, the new setup can derive the oxidation reactivity from isothermal measurements, thus enabling on-line monitoring of the soot oxidation reactivity in transient systems. Isothermal measurements on a real diesel engine were conducted and correlated to different engine and exhaust gas parameters.
AB - Soot particles in the atmosphere significantly affect human health as well as the climate. In order to avoid soot emissions, exhaust gases are filtered and the particles are trapped on a filter. The particles are eventually removed by catalytic oxidation to CO2, a process that requires elevated temperatures. The reactivity, i.e. the temperature required for this process, is currently determined after sample collection by techniques such as temperature-programmed oxidation (TPO), Raman microscopy or high-resolution transmission electron microscopy (HRTEM), which are all time-consuming and expensive. Furthermore, a significant amount of soot has to be collected prior to the analysis. This study aims for a straight-forward method to characterize the oxidation reactivity of exhaust soot on-line. A differential flow-through oven-system was built to thermally treat soot and determine the oxidation losses in comparison to a reference channel. The performance of the system was assessed by propane soot as well as by K2CO3-containing soot, which feature largely different reactivities in earlier studies. The results of the new system are compared to TPO measurements by using the same temperature program. K2CO3-containing soot shows oxidation at significantly lower temperatures than pure propane soot. Photoacoustic spectroscopy (PAS) revealed a considerable temperature-dependent decrease of soot mass concentrations, starting at lower temperatures for the K2CO3-containing soot. Beyond that, the new setup can derive the oxidation reactivity from isothermal measurements, thus enabling on-line monitoring of the soot oxidation reactivity in transient systems. Isothermal measurements on a real diesel engine were conducted and correlated to different engine and exhaust gas parameters.
KW - Diesel emissions
KW - Online analysis
KW - Oxidation reactivity
KW - Photoacoustic mass detection
KW - Soot
UR - http://www.scopus.com/inward/record.url?scp=85063140557&partnerID=8YFLogxK
U2 - 10.1016/j.jaerosci.2019.03.002
DO - 10.1016/j.jaerosci.2019.03.002
M3 - Article
AN - SCOPUS:85063140557
SN - 0021-8502
VL - 132
SP - 12
EP - 21
JO - Journal of Aerosol Science
JF - Journal of Aerosol Science
ER -