REACTIVITY OF CATALYSTS FOR COAL-GASIFICATION - EFFECTS OF GASES FORMED ON REACTIVITY

Steam gasification of three different ranks of coal with or without catalysts was conducted using a vertical quartz tube as the reactor. Various amounts of coal were charged and the effects of pyrolysis/gasification products on the reactivity of coal-catalyst systems were examined. For Taiheiyo coal without added catalyst, carbon conversion per a unit weight of coal decreased with the bed height indicating the suppressive effect of the products. With sodium catalyst, deactivation was almost negligible. With calcium, iron or nickel, the deactivation was intermediate between the sodium-loaded and non-catalytic cases. For Taiheiyo and Loy Yang coals, the composition in CO and CO2 was in equilibrium with the steam partial pressure. This indicates the occurrence of a water gas shift reaction downstream of the reaction bed. For Blair Athol coal, equilibrium was attained only with catalysts active for a shift reaction, i.e., calcium or chromium. The amount of tar decreased for Blair Athol coal with nickel or iron as catalyst suggesting that secondary decomposition occurs for some coal/catalyst systems.