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Soot oxidation kinetics from TG experiments

Can they be used reliably in diesel particulate filter modelling tools?

Journal of Thermal Analysis and Calorimetry
Authors: Maria Kalogirou and Zissis Samaras

Abstract  

Thermogravimetric analysis (TG) has been used extensively for soot oxidation studies. Its known experimental and computational difficulties, however, have led to extended criticism concerning the reliability of the extracted kinetics and their potential for reliable reaction modelling. This study explores if TG kinetics could lead to successful simulation results notwithstanding the related disputes. For this, TG and mini-scale soot oxidation experiments with oxygen (O2) were conducted. The TG kinetics reliability was controlled through comparison with the corresponding mini-scale results and by the satisfactory simulation of the mini-scale experiments.

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Abstract  

Isothermal and non-isothermal thermogravimetric experiments (TG) with real and synthetic (Printex U) soot were performed at different O2 concentrations (5–22%O2/N2), sample masses (0.5–10 mg), heating (5–20 °C min−1) and flow rates (80–100 mL min−1). The significance of the experimental and calculation uncertainties (i.e. experimental parameter dependencies, calculation method and mass transfer limitations), which are related to TG for the extraction of chemical kinetics, was explored. Finally, an intrinsic kinetic equation for soot oxidation is proposed.

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Journal of Thermal Analysis and Calorimetry
Authors: Eudes Lorençon, Rodrigo G. Lacerda, Luiz O. Ladeira, Rodrigo R. Resende, André S. Ferlauto, Ulf Schuchardt, and Rochel M. Lago

significantly when the metal impurity of the sample increased. Iijima et al. [ 13 ] reported that SWNT can be purified by using gold nanoparticles deposited on carbonaceous soot followed by controlled oxidation with O 2 . An overall analysis of these reports

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1 Introduction Diesel engines in recent times have been widely used as a means of transportation. However, these automotive systems suffer from a high level of discharges which are most times soot [ 1–3 ]. In the advent of this, reducing diesel

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Abstract  

Reports suggest KNO3 as the active phase for the catalytic combustion of soot, through a redox mechanism with KNO2. Previously, the high activity of KNO3 for coal gasification (mechanism similar to that of soot combustion) was attributed to decomposition into active KxOy (y < x) compounds. In this work, TGA-MS assays of carbothermic reduction using the KNO3/MgO catalyst showed decomposition into NOx, (to which starting of CB combustion is attributed) and potassium oxide, thus disregarding possible redox cycles KNO3/KNO2. Consecutive assays of carbothermic reduction and TPO in a fixed bed reactor showed the potassium oxides as the main active phases of these catalysts.

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Abstract  

Two isothermal soot oxidation protocols were tested in a Perkin-Elmer TGA6: (1) the sample was heated under N2 and then the reaction gas was introduced and (2) the sample was introduced after the empty furnace was heated under the reaction gas. The first protocol is common in soot oxidation studies, it gives a measure of the volatiles and is easier to handle, but as it is shown the determined reaction rate may be falsified by the O2 concentration. Using gas analysis it was found that ∼2000 s are necessary for the complete gas change in the instrument. An instrument specific correction function involving the O2 concentration and reaction order n with respect to O2 was developed which allowed the correlation of the rates measured with both protocols.

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Various carbon dust particles

Studies on thermal behaviour

Journal of Thermal Analysis and Calorimetry
Authors: Sonja Eichholz, Martin Lerch, Michael Heck, and Dirk Walter

dust particles to human health in more detail, state-of-the-art characterization methods are required. Here, electron microscopy and thermal analysis combined with gas analysis may be taken into account [ 2 , 3 ]. A comparison of diesel soot and carbon

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, we performed temperature-programmed oxidation (TPO) experiments with diesel soot samples using condensable and corrosive reactive gases. In our TPO experiments, the samples were usually heated from 50 to 750 °C at 10 K/min in a feed of 10

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Abstract  

The effects of fullerenes, including fellerene soot (FS), extracted fullerene soot (EFS) and pure C60 on the thermal decomposition of ammonium perchlorate (AP) compared with traditional carbon black (CB) catalyst has been studied by employing thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and ignition temperature experiments. The results showed that the addition of CB and FS to AP reduced the activation energy as well as the temperature at maximum decomposition rate, but that of EFS and pure C60 had little effect on the thermal decomposition of AP, and among all catalysts, FS was the best one.

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