Melissa Dunkle



Melissa received her Ph.D. degree in 2007 under the direction of Prof. Luis A. Colón from the Department of Chemistry at the University at Buffalo, NY, USA. She then completed a two year post-doc at Ghent University in Belgium under the direction of Prof. Dr. Pat Sandra. In 2009, Melissa accepted a role a GC Specialist at the Research Institute for Chromatography (RIC) in Kortrijk; she then joined Dow Benelux BV in 2015 in Analytical Science, Core R&D. Her expertise includes liquid chromatography-high resolution mass spectrometry (LC-HRMS, MS/MS), gas chromatography coupled to various detector technologies (GC-FID, GC-MS, GC-(HR)TOFMS, GC-VUV), supercritical fluid chromatography (SFC), and multidimensional chromatography (LCxLC and GCxGC). In her current role, Melissa leads various research projects to advance analytical capabilities and improve the evaluation of natural gas and circular feedstocks.

Short description about presentation:

The issues around waste plastic have gained global attention, and many Value Chain Partners are working towards a plastics’ circular economy. Dow has evaluated multiple pyrolysis oil samples produced around the world from waste plastics as a potential circular feedstock. Typically, these have been found not suitable to be used as a drop-in replacement of fossil-naphtha to produce circular plastics. To facilitate application of such oils as a circular feedstock, a much better understanding of the pyrolysis oil composition is required. This calls for the development of more advanced characterization techniques to identify a variety of hydrocarbons as well as organic molecules with hetero-atoms such as Cl, O, and/or N.

Pyrolysis oils originating from waste plastic are complex and contain unsaturated hydrocarbons which are not present in fossil feedstocks. Therefore, detailed hydrocarbon analysis (DHA) or GCxGC with FID detection is inadequate to fully characterize the hydrocarbon composition of such samples, especially when peaks are closely eluting, or even co-eluting. In this study, the GC-VUV method previously described for the analysis of liquid hydrocarbon streams has been applied to the analysis of pyrolysis oils. While GC-VUV can provide superior PIONA quantification based on the UV spectra, little information was obtained for the heteroatoms.

Pyrolysis products are also rich in heteroatom containing hydrocarbons, especially oxygen, where commercially available methods are restricted within C1 and C5 oxygenates. To obtain a better understanding of the heteroatom composition, GCxGC coupled to Time of Flight Mass Spectrometry (TOF-MS) was used and preliminary results will be highlighted.