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Pyrolysis-gas chromatographic-mass spectrometric and thermogravimetric-mass spectrometric investigation of brown coals

1985; Elsevier BV; Volume: 8; Linguagem: Inglês

10.1016/0165-2370(85)80030-9

1873-250X

Marianne Blazsó, Tamás Székely, Ferenc Till, Gábor Várhegyi, Emma Jakab, Piroska E. Szabó,

Coal Properties and Utilization

Fourteen low-rank coals were subjected to thermogravimetric-mass spectrometric (TG-MS) and pyrolysis-gas chromatographic-mass spectrometric investigations. TG-MS fragment ion curves were used to clarify the thermal decomposition processes taking place during coal pyrolysis. Carbon dioxide production is attributed to the decarboxylation of humic acid content at 300°C and that of other acidic and ester groups up to 500°C. The pyrolytic evolution of alkylarenes seems to be connected with the production of carbon monoxide, through the cleavage of the ketonic carbonyl groups linking the aromatic segments. Methane originates from long-chain alkanes at about 500°C but from alkyl substituents of arenes at higher pyrolysis temperatures. Above 800°C the dehydrogenation process proved to be a consequence of the aromatic ring destruction reaction at aryl ether bonds. The TG-MS curves serve as an adequate basis for the selection of a suitable temperature for fast pyrolysis applied for the characterization of coals. The relative amounts of the isoprenoid and aromatic marker compounds found in the pyrograms at 600°C proved to be related to the rank of the coal. The coal samples investigated have been characterized by the relative amounts of some pyrolysis products considered to be of key importance.