Using Carbon-14 Isotope Tracing to Investigate Molecular Structure Effects of the Oxygenate Dibutyl Maleate on Soot Emissions from a DI Diesel Engine
The effect of oxygenate molecular structure on soot emissions from a DI diesel engine was examined using carbon-14 (14C) isotope tracing. Carbon atoms in three distinct chemical structures within the diesel oxygenate dibutyl maleate (DBM) were labeled with 14C. The 14C from the labeled DBM was then detected in engine-out particulate matter (PM), in-cylinder deposits, and CO2 emissions using accelerator mass spectrometry (AMS). The results indicate that molecular structure plays an important role in determining whether a specific carbon atom either does or does not form soot. Chemical-kinetic modeling results indicate that structures that produce CO2 directly from the fuel are less effective at reducing soot than structures that produce CO before producing CO2.