Experimental Study of Carbon Black and Diesel Engine Soot Oxidation Kinetics Using Thermogravimetric Analysis

Abstract

Non-catalytic oxidation kinetics of diesel engine soot and more than a dozen commercial carbon black samples was investigated using non-isothermal and isothermal thermogravimetric analysis (TGA) experiments. The effect of various operating parameters, such as oxygen flow rate, initial sample mass, oxygen partial pressure, crucible type, and ramp rate, on the oxidation rate was investigated. Three types of TGA experiments (non-isothermal single-ramp rate, non-isothermal multiple-ramp rates, and isothermal) were conducted and analyzed to extract the kinetic parameters for oxidation. Activation energies for oxidation of carbon black samples ranged from 125 to 257 kJ/mol, whereas that for soot oxidation was ∼155 kJ/mol. Furthermore, oxidation rate trends were explained on the basis of structural characteristics, such as scanning electron microscopy (SEM)-based average particle size and Brunauer–Emmett–Teller (BET) surface area. In general, a low particle size and high surface area were associated with a higher oxidation rate and vice versa. A thorough understanding of the non-catalytic oxidation kinetics developed in this work along with the correlation of the oxidation rate with the structural parameters may assist in efficient oxidation of diesel engine soot during the regeneration of diesel particulate filters.

Optimized Heating Rate and Soot-catalyst Ratio for Soot Oxidation over MoO3 Catalyst

“…Pre-exponential factors in a logarithm form were located within 8.6 and 16.0. Both kinetic parameters of the activation energy and the pre-exponential factor were well conformed with those values found in literatures [6,14].…”

“…It owns a specific surface area of 100 m 2 /g, with an average size of 25 nm and the density of 130 g/L. The carbon black has been traditionally applied to replace diesel soot in TG experiments due to its fine repeatability [6]. The catalyst adopted in this study is a commercial nano-scale molybdenum trioxide MoO3 from Beijing DK Company (purity 99.9%).…”

“…Otherwise, inappropriate setup could make the kinetics-controlled regions deviate into diffusion-controlled regions [6,7]. Especially, the heating rate exerts important effects on results of soot oxidation mainly due to the great influence of temperature on the oxidation reactivity [8].…”

Phy-chemical Attributes of Nano-scale V2O5/TiO2 Catalyst and Its’ Effect on Soot Oxidation

“…Then the square of the Pearson correlation coefficients (R 2 ) and the activation energy values were calculated and given in Table 2. The plots for different samples are almost straight lines with R 2 ≥ 0.968, which agrees with the requirement of FWO method [24,25] As shown in Table 2, the activation energy of soot combustion without catalyst is 175.5 kJ/mol, which is reasonable in statics [25]. The activation energy is supposed as the minimum energy needed to start a chemical reaction.…”

“…The thermal gravimetric experiments of soot in the presence of the catalyst V2O5 (V0, V5, V10, V20, V40) were performed at different heating rates (10,15,20,25, 30 o C/min).…”