Co-pyrolysis behaviors of low-rank coal and polystyrene with in-situ pyrolysis time-of-flight mass spectrometry

Abstract In-situ detection of the primary volatiles is vital for co-pyrolysis interactions of coal and waste plastics, and can reveal their interactions based on the primary volatiles distribution and kinetics. In this study, a novel in-situ pyrolysis time-of-flight mass spectrometry (Py-TOF-MS) was applied to analyze primary volatiles distribution and evolved behaviors of co-pyrolysis of a low-rank Pingshuo coal (PC) and polystyrene (PS), and disclose the interaction mechanisms of PC/PS co-pyrolysis combined with different kinetic models. TG results indicated that the blending ratio of PC to PS being 7:3 has the best interaction in improving volatiles evolved performance. According to in-situ Py-TOF-MS analysis, the addition of PS can promote early release of volatiles from the peak of 418 °C (PC) to 389 °C, and dramatically enhance H-transfer. Among them, the increase of monocyclic aromatic hydrocarbons ascribed to the Diels-Alder and dehydration reaction, while the styrene monomer obviously increases from 2.15% to 7.34% due to the co-pyrolysis enhances the cleavage of Car-Cβ bond on the PS main chain. Moreover, kinetics study identified that the variation of activation energy can provide effective supplements to the co-pyrolysis interactions.