Comprehensive Two-Dimensional Gas Chromatography: A Universal Method for Composition-Based Prediction of Emission Characteristics of Complex Fuels

Abstract

Liquid fuels such as gasoline, kerosene, or diesel exhibit a very complex chemical composition. The transition toward a sustainable world requires the development of novel alternatives to fossil-based light and middle distillates, leading to a further increase in the composition complexity by the introduction of chemical structures absent in fossil fuels. The transfer of fundamental knowledge on molecular behavior in combustion demands in the first place a reliable analysis of the composition of such fuels, containing hundreds of molecules and chemical structures. This study presents a universal comprehensive two-dimensional gas chromatography (GCxGC) method for the complete group-type to component-by-component analysis of fossil and alternative fuels. The emphasis was placed on the optimized separation of hydrocarbon groups in a large number of different synthetic and fossil fuels and their crude products, with simultaneous sensitive detection by mass spectrometry and flame ionization. The optimized analysis method is applicable for the full range of fossil light to middle distillates as well as various synthetic fuels. In addition to the classification and quantification of the composition in up to 20 chemical groups, the method is characterized by the fact that a component-by-component evaluation is possible. This level of detail is suitable to derive chemicophysical and combustion properties solely from the composition analysis. This is demonstrated by the prediction of the sooting behavior of 20 gasoline fuels including various types of alternative non-petroleum fractions. The sooting tendency is obtained from tabulated molecular Yield Sooting Indices (YSI). The results are successfully validated against smoke point and soot precursor species measurements from a molecular-beam mass spectrometry (MBMS) flow reactor experiment.