PROFILING OF THE ORGANIC NITROGEN COMPOUNDS IN MARGINALLY STABLE DIESEL FUELS USING GCXGC-NITROGEN CHEMILUMINESCENCE DETECTION (NCD)

摘要

Previously,a set of low sulfur diesel fuels from the Western Pacific region were found to be unstable during storage although they passed all standard specification tests,thus defining them as"marginally stable".This sample set was found to have high nitrogen content and studies on these fuels by liquid-1iquid phase extractions,GC-MS,and GC-nitrogen phosphorous detection (NPD) revealed a correlation between the basic nitrogen compounds (BNCs) in these fuels and the formation of high levels of particulates in storage.In this study,a two-dimensional gas chromatography with nitrogen chemiluminescence detection (GCxGC-NCD) methodology was developed and validated to more extensively characterize the different classes of organonitrogen compounds in the marginally stable diesel fuels.The findings indicated that the basic nitrogen compounds are not unique to the marginally stable fuels;however,it did identify a lighter polar organonitrogen fraction that had previously not been observed.A survey of stable diesel fuels indicated that this light organonitrogen fraction was unique to the marginally stable fuels.If this is found to be universally applicable,this light polar nitrogen fraction may serve as an indicator of potentially unstable diesel fuels.Compared to the previous nitrogen detection methods,the GCxGC-NCD method has greater compound separation abilities and neat fuels can be injected onto the columns so no sample preparation is involved.Overall,the GCxGC-NCD method has shown to be a valuable tool to enhance our understanding of the chemistry of organonitrogen species and their impact on fuel stability.