Trace species formation pathway analysis of biodiesel engine exhaust

The goal of this study was to derive the possible formation pathways of the trace species detected in the tail-gas of a diesel engine. The biodiesel (SBM) used in this study was converted from soybean oil through transesterification. The converted biodiesel was then used in a four-cylinder, 2200 c.c. diesel engine, and the resulting formation of trace species in the tail gas exhaust was investigated. The major species in SBM’s saturated fatty acid methyl esters (FAMEs) were Methyl palmitate (Hexadecanoic acid methyl ester, C17H34O2, 11.85%) and Methyl stearate (Octadecanoic acid methyl ester, C19H38O2, 6.61%), with Methyl octadeca-9,12-dienoate (9,12-Octadecadienoic acid methyl ester, C19H34O2, 74.78%) as the major species in SBM’s unsaturated FAMEs. The chemical classes of the observed trace compounds were hydrocarbons, aldehydes, carboxylic acids, ketones, alcohols, esters, and others. The trace species formation pathways were then derived based on the major species found in the biodiesel fuel and in its exhaust.