Structure and Oxidation Activity Correlations for Carbon Blacks and Diesel Soot

Abstract

This work focuses on a comprehensive investigation of structure−activity relationships for a diesel engine soot sample (Corning) and 10 commercially available carbon black samples. Particle sizes were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Specific surface area was determined by nitrogen sorption studies, while the microstructure was investigated by X-ray diffraction (XRD) peak profile analysis, Raman spectroscopy, and TEM. Oxidation activity of these samples was studied using thermogravimetric analysis (TGA) under an oxidative (10% O 2 ) environment consistent with the typical oxygen levels in the diesel engine exhaust. Various structural parameters, such as the average particle size, specific surface area, degree of organization, and average crystallite stacking height, were correlated with the TGA oxidation activity data. In general, samples with low particle size, high surface area, highly amorphous nature (low degree of organization), and low crystallite stacking height showed high oxidation activity. A second diesel engine soot sample (Corning), which was collected at different operating conditions, was used to validate the obtained structure−activity correlations. Overall, our rigorous analysis for a large number of samples with multiple techniques indicated unique and novel correlations/trends between soot structure and reactivity.

Low Temperature Desulfurization of H2S: High Sorption Capacities by Mesoporous Cobalt Oxide via Increased H2S Diffusion

“…However, the UCT materials showed significantly higher activities compared to their analogous nonoporous materials due to their mesostructure consists of interconnected intraparticle voids which increase the diffusion of H 2 S(g). 14,39,40 On the basis of the high activity data observed for mesoporous Mn 2 O 3 materials, further studies are being carried out in our laboratories.…”

Soot oxidation performance with a HZSM-5 supported Ag nanoparticles catalyst and the characterization of Ag species

“…However, a diesel engine produces more harmful substances of nitrogen oxides (NO x ) and particulate matter (PM), which mainly consists of soot and a soluble organic fraction (SOF), compared to gasoline-engine vehicles. [1][2][3][4][5] PM, along with serious environmental and health problems, has been one of the main pollutants in air for the last two decades. Many researchers have focused on the development of aertreatment systems for PM.…”

Nanostructure changes in diesel soot during NO2–O2 oxidation under diesel particulate filter-like conditions toward filter regeneration

“…A linked study by the same group 10 showed that soot oxidative reactivity was qualitatively related to its morphology and subsequently to its nanostructure as the primary factor regulating oxidative reactivity. In contrast, several notable works have identified soot ''structure,'' 10,[13][14][15] either understood or named as nanostructure 1,3,16,17 as an essential metric governing soot oxidative reactivity and as consequence, nanostructure has been studied across a variety of fuels and fuel blends under different oxidation conditions. Yet absent from present literature is a study showing comparative nanostructure evolution for conditions of passive DPF regeneration with and without NO 2 at typical exhaust temperatures, as detailed in this article.…”

“…Reactions by NOx, including N 2 O and N 2 O 4 , with associated kinetics, have also been studied and well summarized by Stanmore et al 20 Most works have focused on soot oxidation for DPF regeneration by analyzing reaction kinetics at various temperatures, 11,[22][23][24][25] changing NO 2 and O 2 gas concentrations, 22 with and without the presence of moisture 22 and/or using representative carbon blacks as surrogates for diesel soot. 14,19 Due to the inactivity of O 2 at typical passive regeneration conditions, soot oxidation is initiated by the presence of NO 2 in the exhaust gas. Once the process of oxidation begins, the mechanism has been shown to occur via the formation of surface oxygen complexes (SOCs) as intermediates.…”