Abstract
Steam gasification of several kinds of oil shales was investigated under the conditions of 750-950°C and atmospheric pressure using a fluidized bed reactor. Oil shale was supplied to the reactor in a batch-wise manner after the reactor was heated to a desired temperature. When compared with pyrolysis, the effect of steam was manifested at the temperatures above 850°C to give fuel or synthesis gas. The produced gas was consisted of H2, CO, CO2, and C1-C5 hydrocarbons. The initial stage of the reaction seems to be a rapid pyrolysis of oil shale, which is followed by the slow reaction taking place between steam and coke deposited on the shale. Total gas yield hardly depended on the feeding rate of steam, while the fraction of H2 and CO2 increased with increasing feed rate of steam due to the contribution of the water-gas shift reaction. Total gas yield was markedly increased by use of potassium carbonate as a catalyst. It is considered that oil vapor released from oil shale in the initial pyrolysis and, moreover, the deposited coke are gasified by the action of the catalyst. Potassium carbonate catalyst supported on alumina catalyzed gasification more effectively than supported directly on the oil shale itself. The product gas from the catalytic gasification was more abundant with H2 compared with uncatalyzed gasification.
