Publication Date


Advisor(s) - Committee Chair

John Reasoner, William Lloyd, Rita Hessley, Laurence Boucher

Degree Program

Department of Chemistry


Plasticity, which typically develops at 380-420°C, is a unique property of mid-ranked coals. The phenomenon of plasticity in coals has been known for a long time but is still poorly understood. Even among coals of identical subrank and chemical composition, large differences in plastic behavior are commonly encountered. Plastic coals go through a softening and swelling state upon heating before they resolidify. Concurrent with the plastic state of the coal, thermal decomposition of the coal takes place.

The coking ability of a coal can be directly related to the plasticity of the coal. In liquefaction reactions, plastic coals tend to give higher yields than nonplastic coals, a fact very useful in the synfuel industry. Plastic coals, however, tend to agglomerate in fluidized bed reactors thereby impairing their function. Currently, the ASTM approved method used to determine plasticity is by means of a Gieseler plastometer. Gieselers are inconsistent; therefore, an easier and more efficient method is needed.

A current and widely accepted idea is that the extractable portion of the mid-ranked coal is responsible for initiating the plasticity mechanism. It has been shown that plasticity can be correlated to the total aliphatic C-H content of a bituminous coal. This extractable portion is the bitumen in the coal. It is logical, then, to assume that the bitumen in the coal could be analyzed for the aliphatic content and be used as a predictor of plasticity.

Tetrahydrofuran (THF) was used as the solvent for the Soxhlet extraction of 40 highly characterized bituminous coals. The extracts were purified and analyzed by Fourier Transform Infrared Spectroscopy and Proton Magnetic Resonance Spectroscopy.



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