Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Determination of aromatic and aliphatic C-H groups in coal using Fourier transform infrared spectroscopy

Thesis/Dissertation ·
OSTI ID:5695492
The determination of coal structure is an obdurate problem. Coal is heterogeneous, noncrystalline, and not completely soluble in any known solvent, making spectroscopic analysis of coal especially difficult. Using infrared spectroscopy, information can be gained most readily about hydroxyl, aliphatic C-H, and aromatic C-H groups. The availability of Fourier Transform infrared Spectroscopy (FT-IR) has allowed such information to be obtained faster and more precisely than with earlier vintage dispersive instruments. A method is developed to determine the aromatic and aliphatic C-H content in coal. This involves equating infrared band intensities to elemental hydrogen. This method is initially applied to a set of 11 pyridine coal extracts, also characterized by proton NMR. The NMR measurements of aliphatic and aromatic hydrogen allow direct calibration of the absorption coefficients of appropriate infrared bands. By this means the coefficients determined by relating the infrared band intensities to elemental hydrogen are directly tested. Reasonable agreement between the results from infrared spectroscopy and NMR is obtained. This method is also applied to a set of 35 whole coals and 41 vitrinite concentrate samples. Infrared absorption coefficients and hydrogen content are determined. Aromatic to aliphatic hydrogen ratios thus obtained are compared to those of other workers. Problems associated with equating infrared band intensities to elemental hydrogen are discussed in depth.
OSTI ID:
5695492
Country of Publication:
United States
Language:
English