Kinetic and FT-i.r. studies of the sodium-catalysed steam gasification of coal chars

The catalytic effects of Na₂CO₃, NaHCO₃, NaOH, NaNO₃ and NaCl on steam gasification of coal chars have been studied by gravimetric measurements at temperatures ranging from 600 to 750 °C and at atmospheric pressure. FT-i.r. studies were carried out to determine the nature of the catalyst-coal interaction. All the salts studied, except NaCl, exhibited good catalytic activity. It was found that the gasification rate increased linearly with the sodium/carbon ratio until a saturation point was reached at a value of 0.12. For the same metal/carbon ratio, the sodium salts were less active than potassium salts, however their activities were similar when compared on the basis of cation loading. FT-i.r. studies of devolatilized and partially gasified samples treated with the active salts showed absorption bands at 1675,1450 and 880 cm^?1. Based on the gravimetric and i.r. results obtained, a model for the catalyst-coal interaction is proposed.