CHANGE IN PHYSICAL CHARACTERISTICS OF ROLAND SEAM COAL WITH PROGRESSIVE SOLVENT-EXTRACTION

The physical structure of Roland Seam coal was characterized by studying the surface areas, pore volumes, and pore distributions of raw and extracted coals. BET surface areas were measured by carbon dioxide adsorption at 195 K and nitrogen adsorption at 77 K. Pore volumes were calculated by the difference in the reciprocals of measured apparent and actual densities. Distribution curves were generated by measuring mercury penetration as a function of pressure. The data gathered suggest a micropore structure having a 3.4 nm average diameter and random constrictions of about 0.4 nm. Extraction generates new micropores and degrades the micropore structure for yields in excess of 30%. Changes in the pore distribution and the generation of new pores indicate that resistance to extraction due to the pore structure is minimal; pore-volume data confirm the preferential liquefaction of lower-molecular-weight material. © 1979.