Catalytic Steam Gasification Reactivity of HyperCoals Produced from Different Rank of Coals at 600−775 °C

Abstract

HyperCoal is a clean coal with ash content <0.05 wt %. HyperCoals were prepared from a brown coal, a sub-bituminous coal, and a bituminous raw coal by solvent extraction method. Catalytic steam gasification of these HyperCoals was carried out with K2CO3 at 775, 700, 650, and 600 °C, and their rates were compared. HyperCoals produced from low-rank coals were more reactive than those produced from the high-rank coals. XRD measurements were carried out to understand the difference in gasification reactivity of HyperCoals. Arrhenius plot of ln (k) vs 1/T in the temperature range 600∼825 °C was a curve rather than a straight line. The point of change was observed at 700 °C for HyperCoals from low-rank coals and at 775 °C for HyperCoals from high-rank coals. Using HyperCoal produced from low-rank coals as feedstock, steam gasification of coal may be possible at temperatures less than 650 °C.