Pyrolysis of High Sulfur Indian Coals

Pyrolysis experiments under laboratory conditions for five numbers of high sulfur coal samples from the states of Meghalaya and Nagaland, India, were carried out at temperatures of 450, 600, 850, and 1000 °C, respectively. The yield of products and thermal release of sulfur from these coals are investigated. The distribution of sulfur in the pyrolyzed products, i.e., char/coke, gas, and tar, is also reported. Hydrocarbon and sulfurous gases released at different temperatures were analyzed by a gas chromatograph (GC) with an FID (flame ionized detector) and an FPD (flame photometric detector), respectively. H2S evolution during coal pyrolysis was found to be a function of temperature up to 850 °C. The low concentration of SO2 detected for some of the samples is due to decomposition of inorganic sulphates present. Evolution of methane for the coals tested increases with the increase of temperature. Maximum sulfur release was found in the range of 600–850 °C and has a decreasing tendency from 850–1000 °C, which might be due to the incorporation of sulfur released into the coal matrix. Activation energies for sulfur release were found in the range of 38–228 KJ mol−1, which were higher than the reported activation energies for lignites and bituminous coals mainly due to highly stable organic sulfur functionalities.