Combining pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry with hierarchical cluster analysis for rapid identification of pyrolytic interactions: Case study of co-pyrolysis of PVC and biomass components

Co-pyrolysis of plastic/lignocellulosic biomass mixtures produces an extremely complex assortment of pyrolyzates. In the present work, co-pyrolysis of PVC with cellulose or xylan or milled wood lignin was conducted by employing pyrolysis–two-dimensional gas chromatography–time-of-flight mass spectrometry (Py-GC × GC-TOFMS) with the aim of achieving high throughput and comprehensive analysis of the complex pyrolyzates. Then, hierarchical cluster analysis (HCA), which is an algorithm that groups similar objects into groups called clusters, was applied to accomplish rapid screening for compounds influenced by pyrolytic interactions. This combined approach improved compound separation and identifiability and allowed the subsequent easy identification of new compounds and compounds increased or decreased by pyrolytic interactions during co-pyrolysis. The change in distribution during co-pyrolysis clearly suggests the occurrence of HCl-catalyzed dehydration of anhydrosugars and conversion of methoxyphenols into phenolic compounds. Thus, this study reveals the effectiveness of the approach combining Py-GC × GC-TOFMS with HCA, which promises to contribute to the acceleration of research on pyrolytic interactions. The understanding of pyrolytic interactions gained thereby will be crucial for maximizing the yield and quality of desired chemicals and fuels from plastic/lignocellulosic biomass.