Evaluate the effect of different butanol isomers on engine exhaust soot particles

Abstract

The chemical properties of soot particles are correlate with the catalytic regeneration efficiency of DPF. The surface chemistry of soot particles generated from the combustion of oxygenated fuels merits focused investigation, especially considering that the particle chemistry among isomer fuels remains insufficiently characterized. In this study, the chemical properties and oxidative activity of soot particles from different butanol isomers were analysed by FT-IR, XPS and TGA. The results indicated that, compared with D100, the O/C ratio of oxygenated fuel particles increased by approximately 159–358 % under 1.2 MPa load, whereas the difference was not significant at 0.6 MPa load. The content of oxygenated functional groups on particle surface increased with the load increase. When the load was increased to 1.2 MPa, the C-O (aliphatics) groups in D100 and TB50 particles were converted to C=O groups, while the corresponding groups in other fuel particles were converted mainly to C-O (aromatics) groups. Moreover, IB50 exhibited the smallest sp3/sp2 ratio (0.15 and 0.22 respectively), indicating a low degree of carbon layer disorder, fewer surface defects, and a lower content of aliphatic/oxygenated functional groups, which consequently led to the highest Ea. Linear analysis revealed a high linear correlation between the O/C ratio and Ea. For instance, NB50 had a high O/C ratio (0.3 and 0.62 respectively), resulting in a lower Ea and higher oxidative activity. Furthermore, changes in engine load altered the particle structure. Some functional groups showed little or no linear relationship with the oxidative activity of soot particles at high loads.