TITLE:
Characterization of Tars from the Thermal Processing of Baganuur and Tavan Tolgoi Coals from Mongolia, Using SEC, UV-F, IR and Mass Spectrometry
AUTHORS:
Barnasan Purevsuren, Yadamsuren Davaajav, Sanjaa Batbilig, Jargalsaikhan Namkhainorov, Fatma Karaca, Trevor J. Morgan, Patricia Alvarez Rodriguez, Feng H. Tay, Sergei Kazarian, Alan A. Herod, Rafael Kandiyoti
KEYWORDS:
Mongolian Coals; Tar Preparation; Characterization; Laser Desorption Mass Spectrometry; Thin Layer Chromatography
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.3 No.2,
April
29,
2013
ABSTRACT: Tars from two Mongolian coals (Tavan Tolgoi
and Baganuur) produced by simple distillation have been characterized using
size exclusion chromatography (SEC) with elution in both
1-methyl-2-pyrrolidinone (NMP) and a mixed solvent (NMP and chloroform),
UV-fluorescence in chloroform and NMP, gas chromatography (GC), mass
spectrometry (GC-MS, probe-MS and LD-MS with thin layer chromatography) and infra-red
spectroscopy. The SEC chromatograms using NMP and the solvent mixture NMP: chloroform
indicates that similar conclusions can be drawn from using either eluent. The
synchronous UV-fluorescence spectra were shifted to longer wavelengths in
chloroform solution than in NMP and chloroform may be the better solvent for
these tars prepared without extensive secondary thermal treatment. Infra-red
spectra indicated differences between the two coal tars that reflected their
different ranks, with more oxygenate groups in the lower rank Baganuur coal.
Mass spectrometry (GC-MS and probe-MS) of both coal tars confirmed the presence
of aliphatic components as well as aromatics and the relatively extensive
alkylation of aromatics. Molecular mass ranges indicated for Baganuur tar by
SEC compared well with the mass range by LD-MS although the LD-MS extended to
higher mass values. The high mass fractions of the tars were revealed by
fractionation by thin layer chromatography with the relevant sections of the
developed plates inserted directly into the mass spectrometer; laser desorption
was directly from the surface of the plate. LD-MS of the unfractionated samples
failed to detect the high mass components because of mass discrimination
effects. The high mass components were carried over in the distillation by mass
transfer of vapours into the condenser.