COAL PROPERTIES AND THEIR INFLUENCE ON AIR ACTIVATION

This research sought to determine how the properties of a raw coal inf luence the degree to which it may be activated. Twelve coals were anal yzed using thermogravimetry, mass spectroscopy, mercury porosimetry, n itrogen sorption and infrared spectroscopy, and activated in air, wate r-saturated helium and carbon dioxide. The greatest amounts of surface area using air activation were generated for bituminous coals. To inv estigate possible reasons for the sample-to-sample variation in the am ount of surface area generated, a spline-fitting program was used to g enerate a curve that encloses the surface areas generated for all samp les. The differences between measured surface areas and surface areas predicted by the spline-fitting program were determined. Statistical a nalyses of twenty-two predictor variables suggest that the percent vit rinite present accounts for nearly 73% of the deviation from predicted surface area. The % liptinite + % ash predicts 86% of the deviation a nd the inclusion of two additional variables, the % pyrite and % organ ic S, appear capable of predicting nearly 99% of the difference betwee n measured and predicted surface areas. Increasing amounts of vitrinit e and pyrite appear to increase the surface area generated, while incr easing amounts of liptinite, ash and organic S appear to decrease the surface area generated. Pyrite may act as a catalyst during activation . (C) 1997 Elsevier Science Ltd.