Thermoplastic development of coking and non-coking maceral concentrates and molecular weight distribution of their pyrolysis products

•Vitrinite concentration could not remove or bestow thermoplasticity onto a sample.•Higher yields of pyrolysis products were measured in vitrinite-rich concentrates.•Bimodal molecular weight distribution to ∼1500Da was observed in coking extracts.•Non-coking extracts possessed unimodal molecular wei...

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Bibliographic Details
Published in:Journal of analytical and applied pyrolysis 2018-01, Vol.129, p.72-85
Main Authors: Tran, Quang Anh, Stanger, Rohan, Xie, Wei, Smith, Nathan, Lucas, John, Wall, Terry
Format: Article
Language:English
Subjects:
Coal macerals
Coal pyrolysis
Coking coal
Metaplast
Solvent extract
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Summary:•Vitrinite concentration could not remove or bestow thermoplasticity onto a sample.•Higher yields of pyrolysis products were measured in vitrinite-rich concentrates.•Bimodal molecular weight distribution to ∼1500Da was observed in coking extracts.•Non-coking extracts possessed unimodal molecular weight distributions to only ∼800Da.. A suit of nitrogen-dried maceral concentrates derived from a coking coal and a non-coking coal was investigated to reveal the impact of varying coal main organic constituent, the vitrinite, on their thermoplasticity and pyrolysis products. The thermoplastic development of maceral concentrates during pyrolysis was evaluated via their thermo-swelling and dynamic volatile release. These measurements were then linked to molecular weight distributions of vaporised tars and tetrahydrofuran (THF) extracts obtained from heat-treated samples. Regardless of the vitrinite content, only coking macerals agglomerated during pyrolysis while non-coking macerals retained their powdered structure. This result indicated that although concentrating the vitrinite could alter the extent of coal thermoplasticity, such process could not grant or remove thermoplasticity from a maceral concentrate. This was reflected in the similar molecular weight distribution of solvent extracts produced between the parent coals and their concentrates. In specific, coking concentrates generated extractable materials with a relatively more complex structure, consisting of a bimodal molecular weight distribution with 12–14Da repeating structures at
ISSN:0165-2370
1873-250X
DOI:10.1016/j.jaap.2017.12.001