Identification and classification of components in flash pyrolysis oil and hydrodeoxygenated oils by two-dimensional gas chromatography and time-of-flight mass spectrometry
Hydrodeoxygenated pyrolysis oils (HDO) are considered promising renewable liquid energy carriers. To gain insights in the various reaction pathways taking place during the hydrodeoxygenation reaction of pyrolysis oil, two-dimensional gas chromatography with time-of-flight mass spectrometric analyses (2D-GC–TOF-MS) was applied on the feedstock and product oil. Chromatographic parameters like injection temperature and column choice of the 1D-2D ensemble are discussed. Fractionation of the oils by hexane extraction was applied to show the distribution of analytes over the phases. Some 1000 and 2000 components in the pyrolysis and HDO oil, respectively could be identified and classified. The TOF-MS detection considerably improved the understanding of the molecular distribution over the 1D-2D retention time fields in the contour plot, in order to classify the analytes in functional groups. By group-type classification of the main components (>0.3% relative area), it was possible to characterize the oils by 250 and 350 analytes, respectively pyrolysis oil and HDO oil, describing 75% of the chromatographable fraction. The 2D-GC–TOF-MS method showed to be a useful and fast technique to determine the composition of (upgraded) pyrolysis oil and is potentially a very useful tool for exploratory catalyst research and kinetic studies. The 2D-GC–TOF-MS technique is not only useful for the chemical study as such, but also provides the basic knowledge for method transfer to a 2D-GC-FID (flame ionization detector) application.