Gum and coke formation due to a high amount of diolefins in mixtures like thermally cracked naphtha are the trigger for problems during pipelining and refining processes. Identifying the diolefin species present in cracked naphtha is the first step towards developing a mitigation strategy. Identifying the diolefins in cracked naphtha is challenging due to the variety of compounds present in the naphtha along with the low concentration of the molecules of interest. The analytic approach followed employed gas chromatography coupled with mass spectrometry in combination with two reactive preparation procedures. Hydrogenation at mild conditions served to identify potential olefins and diolefins by comparing chromatograms before and after reaction. Knowing that conjugated diolefins undergo electrophilic additions, the Diels-Alder reaction was likewise used to identify potential conjugated diolefins. Identification by mass spectrometry was confirmed when practical by model compounds. All of the diolefins were found to be in the C<sub>5</sub> to C<sub>7</sub> carbon number range, although the presence of heavier diolefins could not be ruled out with certainty due to the complexity of the matrix.

Diolefin characterization in thermally cracked naphtha

251st National Meeting (2016)

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