Thermal fragmentation and deactivation of combustion-generated soot particles
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Advanced Nanofabrication, Imaging and Characterization Core Lab
Clean Combustion Research Center
Combustion and Laser Diagnostics Laboratory
Imaging and Characterization Core Lab
Mechanical Engineering Program
Physical Sciences and Engineering (PSE) Division
Water Desalination and Reuse Research Center (WDRC)
Permanent link to this recordhttp://hdl.handle.net/10754/563733
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AbstractThe effect of thermal treatment on diesel soot and on a commercial soot in an inert environment under isothermal conditions at intermediate temperatures (400-900°C) is studied. Two important phenomena are observed in both the soot samples: soot fragmentation leading to its mass loss, and loss of soot reactivity towards O2. Several experimental techniques such as high resolution transmission electron microscopy, electron energy loss spectroscopy, thermo-gravimetric analysis with mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction have been used to identify the changes in structures, functional groups such as oxygenates and aliphatics, σ and π bonding, O/C and H/C ratios, and crystallite parameters of soot particles, introduced by heat. A decrease in the size of primary particles and an increase in the average polycyclic aromatic hydrocarbon (PAH) size was observed in soots after thermal treatment. The activation energies of soot oxidation for thermally treated soot samples were found to be higher than those for the untreated ones at most conversion levels. The cyclic or acyclic aliphatics with sp3 hybridization were present in significant amounts in all the soot samples, but their concentration decreased with thermal treatment. Interestingly, the H/C and the O/C ratios of soot particles increased after thermal treatment, and thus, they do not support the decrease in soot reactivity. The increase in the concentration of oxygenates on soot surface indicate that their desorption from soot surface in the form of CO, CO2 and other oxygenated compounds may not be significant at the temperatures (400-900°C) studied in this work. © 2014 The Combustion Institute.
SponsorsThis work has been supported by Saudi Aramco, KSA through KAUST CCRC and the Petroleum Institute, UAE.
JournalCombustion and Flame