THE LOW-TEMPERATURE OXIDATION PROCESS IN AN ALBERTA HV BITUMINOUS COAL AS MONITORED USING THE 9GHZ CW-EPR MN2+ HFS SPECTRAL PARAMETER

The low temperature oxidation process in dried and moisture saturated samples of an Alberta hy bituminous coal containing approximately 237 ppm manganese impurity ions subjected to dry air flow has been studied using dynamic in situ 9 GHz continuous wave-electron paramagnetic res onance (CW-EPR) in the temperature interval from 293 to 523 K. It was found that there is a correlation between oxidation, as indicated by a n increasing concentration of carbon free radicals, and the presence o f moisture and inorganic matter as monitored by the Mn2+ spin concentr ation. Arrhenius plots were used to characterize the changes in the sp in concentration which were observed during the low temperature oxidat ion process. It was found that the lower values of the apparent activa tion energy can be attributed to solid (carbonyl and carboxyl) rather than gaseous oxidation products, and that these activation energy valu es depend on the sample pretreatment procedure. This kinetic analysis also has provided evidence for the existence of reactions involving ch anges in the oxidation state of the Mn ions which occur in characteris tic temperature intervals.