Identification of engine oil-derived ash nanoparticles and ash formation process for a gasoline direct-injection engine
| Autor: | Sungsik Lee, Seungmok Choi, Tianpin Wu, Huifang Shao, Joseph E. Remias, Nestor J. Zaluzec, Heeje Seong |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
010504 meteorology & atmospheric sciences Health Toxicology and Mutagenesis 010501 environmental sciences Toxicology medicine.disease_cause Combustion 01 natural sciences medicine Particle Size Gasoline direct injection Vehicle Emissions 0105 earth and related environmental sciences Diesel particulate filter General Medicine Particulates Fuel injection Pollution Soot Chemical engineering Nanoparticles Particle Particulate Matter Particle size Oils Gasoline |
| Zdroj: | Environmental Pollution. 272:116390 |
| ISSN: | 0269-7491 |
| DOI: | 10.1016/j.envpol.2020.116390 |
| Popis: | Engine oil-derived ash particles emitted from internal combustion (IC) engines are unwanted by-products, after oil is involved in in-cylinder combustion process. Since they typically come out together with particulate emissions, no detail has been reported about their early-stage particles other than agglomerated particles loaded on aftertreatment catalysts and filters. To better understand ash formation process during the combustion process, differently formulated engine oils were dosed into a fuel system of a gasoline direct injection (GDI) engine that produces low soot mass emissions at normal operating conditions to increase the chances to find stand-alone ash particles separated from soot aggregates in the sub-20-nm size range. In addition to them, ash/soot aggregates in the larger size range were examined using scanning transmission electron microscopy (STEM)-X-ray electron dispersive spectroscopy (XEDS) to present elemental information at different sizes of particles from various oil formulations. The STEM-XEDS results showed that regardless of formulated oil type and particle size, Ca, P and C were always contained, while Zn was occasionally found on relatively large particles, suggesting that these elements get together from an early stage of particle formation. The S, Ca and P K-edge X-ray absorption near edge structure (XANES) analyses were performed for bulk soot containing raw ash. The linear combination approach & cross-checking among XANES results proposed that Ca5(OH)(PO4)2, Ca3(PO4)2 and Zn3(PO4)2 are potentially major chemical compounds in raw ash particles, when combined with the STEM-XEDS results. Despite many reports that CaSO4 is a major ash chemical when ash found in DPF/GFP systems was examined, it was observed to be rarely present in raw ashes using the S K-edge XANES analysis, suggesting ash transformation. |
| Databáze: | OpenAIRE |
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