Impact of Lubricant Metallic Elements on Oxidation of Combustion Particulate Matter in Diesel Engines

Focusing on the influence of lubricant additives on diesel particulate filter regeneration and the oxidation process of particulate matter, research on the oxidation characteristics and oxidation process of diesel engine combustion particulate matter by metal components of lubricant additives was carried out. A test rig of a four-cylinder diesel engine was built, lubricant additives containing different metal elements were used, diesel engine combustion particulate matter was collected, and the surface functional groups and oxidation characteristics of the particulate matter were investigated. Ash containing different metal elements was blended with Printex-U(PU) carbon black, and the elemental composition of the samples was analyzed. Samples of the particulate matter with different oxidation conversion rates were prepared, and the microscopic morphology of the samples was analyzed. The results showed that all the lubricant additives increased the oxidation activity of particulate matter, shortened the oxidation time, and reduced the onset temperature of oxidation; the antioxidant and corrosion inhibitor had the smallest decrease in the activation energy of the particulate matter, and the extreme pressure (EP) additive had the largest increase in the oxidation activity of the particulate matter; the blending of the ash enhanced the ratio of adsorbed oxygen (Oa)/lattice oxygen (O1) and the sp3/sp2 hybridization of the samples, which led to an increase in the oxygen active sites increased; the particulate matter agglomerated more tightly after the ash blending; and the area of the hollow structure of the sample increased with the increase of oxidative conversion rate, which was conducive to the enhancement of the oxidative activity of the particulate matter.