Relationship between the Gasification Reactivity and the Properties of the Chars prepared from an Australian Brown Coal by Several Methods

The gasification reactivity of the chars prepared from an Australian brown coal, Morwell, by several methods was measured, and was correlated with several char properties. Although the chars were prepared at the same temperature of 750° under the same heating rate, the char yield, the pore surface area and the ultimate analysis varied significantly depending on the coal pre-treatment method and/or the atmosphere during the pyrolysis. The pore surface area, for example, ranged from 240 to 520×103m2/kg, and the oxygen content varied also from 8.9 to 21.6%. The gasification rate of the char prepared from a coal-methanol mixture was only one-tenth of the char prepared from the raw coal. The reaction rate of the char prepared from a coal pre-swollen with tetralin was almost similar to the reaction rate of the char prepared from the raw coal, although the char yield of the former sample was smaller than that of the latter sample by 10kg/100kg-coal. An excellent correlation whose correlation coefficient was 0.99 was obtained between the gasification rate and the oxygen content of the char. This is because the oxygen content measured in this work well corresponds to the amount of active site of the char.