Products from the rapid pyrolysis of a brown coal in inert and reducing atmospheres

Abstract

Yallourn brown coal and its calcium form have been pyrolysed in three different gas mixtures: 23% methane in argon, 50% hydrogen in argon, and 9.4% toluene in argon, at heating rates of 10 7Ks −1 and residence times of ≈2 ms. The products have been compared with those obtained in pure argon. The highly reactive molecule, ketene, was detected in the pyrolysate gases from both the ‘raw’ and calcium-form coals when pyrolysed in the above mixtures. Ketene was not detected in the pyrolysate gases, however, when the coals were pyrolysed in argon alone. When pyrolysed in 23% methane/argon the maximum yield of carbon monoxide from the ‘raw’ coal was found to be much lower than when pyrolysed in pure argon. The fully exchanged calcium-form coal when pyrolysed in pure argon, gave a maximum yield of carbon dioxide of oxygen content equal to the total oxygen content of the carboxyl groups originally present in the coal; the C0 2 yield from the ‘raw’ coal was about half that from the calcium-form in pure argon.