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Proceedings Paper

Infrared Microspectroscopy Of Coals
Author(s): Douglas Brenner
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Paper Abstract

Coals consist of a wide range of plant matter which has undergone metamorphosis, as well as various minerals. The organic matter in the coal contains the remnants of a variety of parts of plants such as trunks, bark, roots, stems, leaves, spores, and so forth. The various coherent remnant organic bodies in the coal, which are generally of microscopic dimensions, are termed "macerals." Most analyses of the chemical functionalities in coals use the coal in a ground-up particulate form which contains a huge variety of different macerals as well as minerals. Such analyses give only averaged information, rather than being characteristic of any individual component of the coal. Now, however, a new microscopic IR (infrared) spectroscopy technique makes possible the chemical analysis of individual macerals of coal. Areas as small as 25 micrometers across can be analyzed. The technique utilizes a computer-controlled IR microspectrophotometer (which is now commercially available) in conjunction with newly-developed procedures for preparing uncontaminated thin sections of coals. The sample preparation technique utilizes a hydrocarbon-soluble adhesive to cement the coal to a glass slide for final grinding. This enables removal of the adhesive with a solvent to produce an uncontaminated specimen. A suitable thickness for the specimens has been found to he roughly 15 micrometers. Using this technique variations from specimen to specimen within a given maceral type, or even heterogeneities within a single maceral, can be determined. Preliminary experiments using this new technique have been made on single macerals of homogeneous vitrinite and liptinite in Illinois No. 6 coal. The spectra clearly contrasted the more aromatic and hydroxyl-containing structure of the vitrinite to the more aliphatic structure of the liptinite. In this paper, details of this new technique are discussed, and recent results, including representative spectra, are presented.

Paper Details

Date Published: 4 November 1983
PDF: 5 pages
Proc. SPIE 0411, Electro-Optical Instrumentation for Industrial Applications, (4 November 1983); doi: 10.1117/12.935771
Show Author Affiliations
Douglas Brenner, Exxon Research and Engineering Company (United States)

Published in SPIE Proceedings Vol. 0411:
Electro-Optical Instrumentation for Industrial Applications
Robert A. Carella; Frederic M. Zweibaum, Editor(s)

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