COMPARISON OF THE LIQUEFACTION YIELDS OF COALS WITH THEIR COMPOSITION, FREE-RADICAL DENSITY AND THERMAL PARAMETERS

Pyrolysis behaviour of four coals, a vitrinite, and a bituminite sample has been investigated between 25°C and 600°C by in situ electron spin resonance (ESR) spectroscopy, thermogravimetry/differential thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) and the results are compared with the percentage conversion of these samples to pyridine-soluble liquefaction products. The three distinct temperature stages of pyrolysis reported earlier by Seehra et al. in ESR spectroscopy are observed in these samples also. Linear regression analysis is used to ascertain correlation between percentage conversion and compositional and thermal parameters. Among the compositional parameters, the best correlation is obtained with the atomic H/C ratio (correlation coefficient, r = 0.82) and among the thermal parameters, the rate of mass loss measured in DTG gives the best correlation (r=0.92), followed by the rate of thermally generated free radicals in stage 3 (r=0.72). The significance of these results is discussed. © 1990.