Comparative studies on low-temperature pyrolysis products of pure PEG and PEG/nano-Co₃O₄by Py-GC/MS

Abstract

Pure PEG (p-PEG) and PEG/nano-Co₃O₄(PEG/n-Co₃O₄) were pyrolyzed in helium atmosphere from 30 °C to 350 °C with heating rate of 20 °C/min, and the online volatile pyrolysis products were detected by a coupled gas chromatography/mass spectrometry (GC/MS). Seven series of products and four linear end groups (ethyl ether, vinyl ether, hydroxyl and methyl ether) from p-PEG pyrolysis were identified. Eight series of products from PEG/n-Co₃O₄pyrolysis were identified, including four series with cycloether end group which was not detected from p-PEG pyrolysis. The end groups of the detected pyrolysis products, both linear and cycloether end groups, could be explained via free radical degradation decomposition pathway. The detected cycloether end group was considered to be derived from dehydrogenation and cyclization of a free radical resulted from CO cleavage, with the existence of nano-Co₃O₄. The statistical results of the contents of the end groups showed that nano-Co₃O₄reduced the probability of CC cleavage comparing with CO cleavage, and induced the hydrogenation of vinyl ether end group on its surface. The statistical results also confirmed the presumed approach of the cycloether end group forming.