Influence of chemical treatments on the behaviour of a bituminous coal in thermal analyses

The influence on its thermal behaviour of the structural modifications afforded to a bituminous coal by several chemical treatments (reduction, alkylation, oxidation followed by butylation) was studied by thermogravimetry (TGA) and oxidative pyrolysis (Ox-Py). The results were discussed in relation to the structural information already obtained by infrared spectroscopy and with the rheological properties characterized by thermomechanical analysis. These results pointed out that the classical behaviour of the bituminous coal is highly modified after chemical treatments. For example, the weakening of the intermolecular interactions, after alkylation, is evidenced by the increase of the weight losses between 180 and 800 degrees C (up to 90-95% after O-butylation).