Deciphering synergistic effects in co-pyrolysis: Insights from pyrolysis-gas chromatography-mass spectrometry and evolved gas analysis for sustainable biorefineries

Harnessing synergistic interactions during co-pyrolysis provides a cost-effective and resource-efficient alternative to catalytic pyrolysis for optimizing product composition and quality. Despite recent progress in understanding these interactions, a systematic method to deconvolute the effects of synergism on bio-oil composition during co- pyrolysis has remained elusive. This study presents a novel method for deconvoluting synergistic effects during the co-pyrolysis of sewage sludge (SS) and polyethylene terephthalate (PET) using unique sample configurations and pyrolysis gas chromatography-mass spectrometry (Py-GCMS). Synergistic interactions during SS/PET co- pyrolysis were found to enhance decarboxylation and dehydration reactions, leading to the formation of novel compounds not observed in the individual pyrolysis of either feedstock. By utilizing unique sample configurations, the developed method identified vapor-phase interactions as the primary interface for these synergistic effects. Additionally, it determined the optimal co-pyrolysis conditions for maximizing benzoic acid production, demonstrating its dual effectiveness in uncovering synergistic mechanisms and optimizing product yields for biorefining applications. Overall, the developed method streamlines the deconvolution of synergistic interactions, making it a valuable tool for understanding synergistic interfaces and optimizing product yields for biorefining applications.