The recent development of comprehensive two-dimensional gas phase chromatography (GC*GC) over the last years has been a turning point in the molecular characterization of gas-oils. The presentation will describe the advances obtained by IFP in the characterization of hydrocarbons, sulfur and nitrogen compounds.
GC*GC hyphenated with a flame ionisation detector allows a detailed quantification of hydrocarbons both by families and by numbers of carbon atoms. This technique can especially be applied to the quantification of mono, di and tri-aromatics, as well as mono, di and tri-naphtenes.
The use of specific detectors based on chemiluminescence enables to separate and quantify sulfur and nitrogen species. Through the sulfur speciation method, alkylated benzothiophenes and dibenzothiophenes from diesel feeds are separated and quantified by numbers of carbon atoms. On the other way, the nitrogen speciation method developed in IFP allows an unambiguous separation of basic and non basic compounds into well defined families (pyridines, anilines, quinolines, acridines, indoles, carbazoles). Both speciation techniques have recently been applied to diesel HDT products, allowing the identification and quantification of the most refractory compounds towards hydrodesulfurization and hydrodenitrogenation.
Therefore, GC*GC offers an interesting perspective in the monitoring of reactions involved in hydrotreatment processes.