Changes in moisture parameters of higher rank coals on low temperature heat treatment

摘要

A scries of low temperature heat treatments of three different coals in a flow of moist air are shown to induce marked changes in moisture equilibrium values at short treatment times. Changes in the chemical functional groups, within and on the surface of the coal have been followed by DRIFT and MASC~(13)SSNMR spectroscopy. The formation of C-0 single bonds is a major pathway of oxidation in early reactions. These lead to the C=O functionalities conventionally observed. The progressive chemical changes observed here may explain in part the observed variations in the moisture uptake and equilibrium moisture content of all three coals reported in this study.