Microcrystal Structure and C/O Element Occurrence State of Diesel PM by Non-Thermal Plasma Oxidation at Different Reaction Temperatures

摘要

To reveal the effect of reaction temperature on the reduction of diesel particulate matter (PM) by non-thermal plasma (NTP) using oxygen as a gas source. The changes in the microcrystalline structure and the elemental state of PM before and after NTP oxidation at different temperatures were explored by Raman and X-ray photoelectron spectroscopy. After NTP oxidation, the disorder in the PM microcrystal structure and the amorphous carbon structure was reduced. The full width at half maximum (FWHM) of the D1 and D3 peaks decreased, and the FWHM of the G peak increased slightly. During the oxidation of PM, the carbon microcrystals grew and became restructured, and the graphitization of PM increased. After NTP oxidation, the content of O in PM increased as the reaction temperature increased, resulting in a gradual change in the binding form of O with C from C-O to C=O. The ability of temperature rise to promote the oxidation activity of NTP was gradually weakened for the thermal decomposition of NTP active substances. The microcrystalline structure and the occurrence state of C and O of PM changed with reaction temperature, indicating that the oxidizability of NTP on PM differed at different reaction temperatures.