THERMAL-CONVERSION OF COAL-LIQUEFACTION RESIDS - TEMPERATURE-PROGRAMMED ELECTRON-SPIN-RESONANCE AND THERMOGRAVIMETRIC INVESTIGATIONS

Ten samples of tetrahydrofuran-soluble distillation resid materials ob tained from the Wilsonville Direct Coal Liquefaction Facility are anal yzed employing temperature-programmed electron spin resonance (ESR) sp ectroscopy and thermogravimetric analysis (TGA). These resids have ato mic C/H ratio varying between 0.90 and 1.20. Experiments were carried out in flowing N2 and H-2 gases near ambient pressures for temperature s up to 600-degrees-C in TGA and up to 500-degrees-C in ESR, in order to determine their thermal behavior and potential for hydrogenation. I n TGA, most of the weight loss occurred between 300 and 500-degrees-C, it was greater in flowing H-2 than that in flowing N2, and excess wei ght loss in H-2 varied directly with the C/H ratio of the resids. In E SR, the free radical densities N at room temperature are smaller by ab out an order of magnitude as compared to N values in bituminous coals and these vary directly with C/H indicating that the lower the N, the more hydrogenated the resid. For all samples, an order of magnitude in crease in N is observed between 100 and 200-degrees-C without weight l oss in TGA and at temperatures above 300-degrees-C, about fifty-fold i ncrease in N is observed presumably due to thermal cracking. For sampl es with larger C/H, the effect of H-2 is to lower their free radical d ensity. These experiments show that hydrogenation amenability of the r esids varies directly with their atomic C/H values. It is suggested th at additional cracking of the resids between 100 and 200-degrees-C may be possible with suitable catalysts and/or processes and weight loss in TGA represents conversion to lighter fractions which here equals th e aliphatic components.