Comprehensive chemical description of pyrolysis chars from low-density polyethylene (LDPE) by thermal analysis hyphenated to different mass spectrometric approaches

20 August 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The production and demand of plastics has drastically increased, with severe environmental impact. Waste incineration is not favored, and efficient recycling strategies are needed. Pyrolysis is a promising approaches but the nature of the residual char is not fully understood. To explore the value of this feedstock, thermal analysis with mass spectrometric detection is deployed. With soft photoionization, we were able to identify alkenes, dienes, and polycyclic aromatic hydrocarbons, which were emitted at four distinct mass loss events. Resonance-enhanced multiphoton ionization allows selectively addressing the aromatic constituents. Interestingly, we found an enrichment of UV-stabilizers, such as benzophenone, within the macromolecular nature. High-resolution mass spectrometry addressing the isobaric complexity and pyrolysis gas chromatography was used for structural elucidation. We hypothesize island- and archipelago-type structural motives comparable to asphaltenes but with almost no heteroatoms. The in-depth chemical description of plastic pyrolysis coke will be valuable knowledge in reactor design and material science.


thermal analysis
mass spectrometry

Supplementary materials

Supplemental Material
Tabular information about the applied process parameters (Table S1), tabular information about the pyrolysis gas chromatographic results (Table S2), Total ion count versus temperature for the empty crucible and pure carbon rods (Figure S1), results of the thermal analysis of pure polyethylene sample with REMPI (Figure S2), Small molecule analysis results of the hyphenation of TG-QMS (Figure S3), compound class distribution of the high-resolution mass spectrometric analysis (Figure S4), Kendrick mass defect plot of the thermal analysis FT-ICR MS (Figure S5), and visualization of the isobaric complexity by enlargement of a nominal mass (Figure S6).


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