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Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends

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ABSTRACT

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

No MeSH data available.


Curve-fitted for the first-order Raman spectra of PM samples: (a) P0, (b) P10, (c) P20 at low load and (d) P0, (e) P10, (f) P20 at high load. G, D1, D2, D3 and D4 bands exhibit after fitting.
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f7: Curve-fitted for the first-order Raman spectra of PM samples: (a) P0, (b) P10, (c) P20 at low load and (d) P0, (e) P10, (f) P20 at high load. G, D1, D2, D3 and D4 bands exhibit after fitting.

Mentions: All PM samples exhibited similar spectra, but the information in the graphite structure was significantly different. Figure 7 shows the fitting results of the first-order Raman spectra of PM samples. In addition to the original D1 and G bands, D2 (1620 cm−1), D3 (1500 cm−1) and D4 (1180 cm−1) bands are exhibited after fitting. The D2 band can be observed as a shoulder on the G band which is attributed to a vibration mode with E2g symmetry involving surface graphene layers40. The D3 band is indicative of amorphous carbon within the PM sample including organic molecules, fragments or functional groups41. The intensity of the D3 band relates to organic molecules, fragments and functional group contents in the PM. The D4 band is usually a lower energy shoulder of D1 which is due to sp2-sp3 bonds or C-C and C=C stretching vibrations of polyene-like structures42. As shown in Fig. 7, the intensity of the D1 band is stronger compared to the G band, indicating poor order of the PM samples. The D3 and D4 bands are weaker in intensity but wider in FWHM implying amounts of amorphous carbon in the PM.


Experimental investigation into the oxidation reactivity and nanostructure of particulate matter from diesel engine fuelled with diesel/polyoxymethylene dimethyl ethers blends
Curve-fitted for the first-order Raman spectra of PM samples: (a) P0, (b) P10, (c) P20 at low load and (d) P0, (e) P10, (f) P20 at high load. G, D1, D2, D3 and D4 bands exhibit after fitting.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5120283&req=5

f7: Curve-fitted for the first-order Raman spectra of PM samples: (a) P0, (b) P10, (c) P20 at low load and (d) P0, (e) P10, (f) P20 at high load. G, D1, D2, D3 and D4 bands exhibit after fitting.
Mentions: All PM samples exhibited similar spectra, but the information in the graphite structure was significantly different. Figure 7 shows the fitting results of the first-order Raman spectra of PM samples. In addition to the original D1 and G bands, D2 (1620 cm−1), D3 (1500 cm−1) and D4 (1180 cm−1) bands are exhibited after fitting. The D2 band can be observed as a shoulder on the G band which is attributed to a vibration mode with E2g symmetry involving surface graphene layers40. The D3 band is indicative of amorphous carbon within the PM sample including organic molecules, fragments or functional groups41. The intensity of the D3 band relates to organic molecules, fragments and functional group contents in the PM. The D4 band is usually a lower energy shoulder of D1 which is due to sp2-sp3 bonds or C-C and C=C stretching vibrations of polyene-like structures42. As shown in Fig. 7, the intensity of the D1 band is stronger compared to the G band, indicating poor order of the PM samples. The D3 and D4 bands are weaker in intensity but wider in FWHM implying amounts of amorphous carbon in the PM.

View Article: PubMed Central - PubMed

ABSTRACT

This paper focuses on oxidation reactivity and nanostructural characteristics of particulate matter (PM) emitted from diesel engine fuelled with different volume proportions of diesel/polyoxymethylene dimethyl ethers (PODEn) blends (P0, P10 and P20). PM was collected using a metal filter from the exhaust manifold. The collected PM samples were characterized using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The TGA results indicated that the PM produced by P20 had the highest moisture and volatility contents and the fastest oxidation rate of solid carbon followed by P10 and P0 derived PM. SEM analysis showed that PM generated from P20 was looser with a lower mean value than PM emitted from P10 and P0. Quantitative analysis of high-resolution TEM images presented that fringe length was reduced along with increased separation distance and tortuosity with an increase in PODEn concentration. These trends improved the oxidation reactivity. According to Raman spectroscopy data, the intensity, full width at half-maximum and intensity ratio of the bands also changed demonstrating that PM nanostructure disorder was correlated with a faster oxidation rate. The results show the use of PODEn affects the oxidation reactivity and nanostructure of PM that is easier to oxidize.

No MeSH data available.