Effect of ash in biodiesel combustion particulate matter on the oxidation characteristics of carbon soot

Abstract

This study investigates the effect of ash in biodiesel combustion particulate matter on the oxidation characteristics of carbon soot within a diesel particulate trap. Samples of pigment-U engineered carbon soot were mixed with different biodiesel ashes using an impregnation method. The samples were subjected to 24 h of heating at 120 °C and 2 h of heating at 350 °C before treatment. The oxidation activity, structural properties and the elemental species of the manufactured carbon soot were investigated using thermogravimetric analysis, specific surface area and pore analysis, Raman spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The oxidation characteristics of the carbon soot were investigated with different metal elements, masses and metal salt types. The results show that the doping of metal elements and metal salt types can increase the oxidation activity of the carbon soot, with Na elements and nitrate having the greatest effect on the oxidation activity. Doping with metal elements and metal salt species can make the structural orderliness and graphitization of the soot decrease, and the O and CO contents increase to different degrees. Sodium (Na) and nitrate have the greatest influence on the soot structural properties, with the numerical ratios and area ratios between peaks being the largest. Doping with Na results in an ID1/IG value of 1.44, and an AD3/AG value of 1.53. The CO content of soot doped with Na is the greatest, reaching 4.7%. The oxygen content of soot doped with Na carbonate is the largest, reaching 5.5%.