Quantitative analysis of Aliphatic Olefins in alternative and petroleum-based fuels by comprehensive two-dimensional gas chromatography

There has been a significant accumulation of plastic waste in landfills and the environment in the past few decades, totaling over 6 billion tons. To reduce the amount of plastic waste, conversion methods such as pyrolysis and hydrothermal processing are used to make oils, which are further used to produce monomers in steam cracking or alternative fuels. Alkene (olefin) content in these oils can range from a few ppm to tenths of a wt.%. However, there are currently no methods for detailed quantitation of olefins, which would not require utilizing of mass spectrometry detector and identifying peak by peak in the respective area of GC chromatogram. In this work, we developed a novel method applicable for the characterization and quantitation of aliphatic olefins in complex oils from plastic depolymerization, alternative, and petroleum-based fuels. Comprehensive two-dimensional gas chromatography with flame ionization detector (GC×GC-FID) and the derivatization method utilizing DMDS was used for this analysis. This method was validated using olefin standards ranging from C₆ to C₂₄ from all aliphatic hydrocarbon classes (n-, iso-, cyclo-). The olefin content (in the range of 0–50 wt.%) in 20 crude and hydroprocessed oils made from plastic waste pyrolysis were determined using GC×GC-FID. Results were compared to those obtained via ASTM D1159 (Bromine Number), ASTM D5554 (Iodine value), and the FIA method.