QUANTIFICATION OF ORGANIC OXYGEN SPECIES ON THE SURFACE OF FRESH AND REACTED ARGONNE PREMIUM COAL

X-ray photoelectron spectroscopy (XPS) was used to determine the kinds of organic and inorganic oxygen species present in Argonne Premium coal. In most cases the XPS results for organic oxygen with fresh coal compare favorably with other methods of analysis. The evolution of CO2, CO, and H2O during pyrolysis at 400 degrees C was quantified, and their appearance was associated with the loss of hydroxyl and carboxyl groups in fresh coal. Oxidation of fresh coal at 125 degrees C in air resulted in significant increases in the level of iron and inorganic sulfate on the coal surface. Oxidation of subbituminous and lower rank coal resulted in increases in the level of carboxyl species but decreases in the level of hydroxyl species. The levels of carboxyl, carbonyl, and other species increase upon oxidation of bituminous and higher rank coal. The advantages and limitations of the XPS approach for quantifying organic oxygen functionalities in coal are discussed.