Surface areas of most American coals are small when measured by N2 adsorption at 77 K and large when measured by CO2 adsorption at 298 K, implying that the majority of the pores are less than 5 Å in diameter. This small pore size would restrict many gaseous and liquid reactants from entering the internal pore system of the coal, and hence, reduces the efficiency of coal conversion. Therefore, if the surface area, as measured by N2 (77 K), could be increased, that is, to increase the pore size, the conversion of coal into useful products should be accomplished more efficiently. Determining the surface properties of coal during treatment is important if one wishes to maximize any future process. Therefore, this research project is undertaken to gain knowledge of the surface properties (in particular the surface area) of coals undergoing treatment with various gaseous and liquid reactants. In particular, the effects of heat treatment in a stream of N2 up to 600oC and of oxidation in a stream of O2:N2 (5%:95%) at various temperatures between 350° and 450°C are studied with three coals of various ranks. The effect of pyridine extraction, at room temperature, before heat and oxidation treatments are examined for two of the coals, in addition to treatment with chromyl chloride at l00°C. Finally, the effects of hydrogen and oxygen atoms on the surface area of the coals are also investigated.

The possibility of increasing the amount of readily accessible surface area by enlarging the 5 A pore was examined via pretreating the PSOC-371 coal with gases such as nitrogen, nitrogen-oxygen, and ozone-oxygen and hydrogen peroxide solutions. Surface areas were obtained from nitrogen adsorption at 77 K and carbon dioxide adsorption at either 298 or 195 K for each sample before and after treatment.