酸化鉄を含む溶融酸化物とCO_2-COガス間の酸素交換反応(高温プロセス基盤技術)

概要

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Oxygen exchange reaction rates between CO_2-CO gas and molten oxides containing iron oxide have been measured by isotope exchange technique with ^<18>O at 1773K with P_<CO_2>/P_<CO>=1. Measured results represent that the oxygen exchange reaction rates show the maximum values at the beginning of the reaction and sharply decrease within approximately 20 s, and then gradually decrease with the reaction time proceeds. These changes indicate that the rate-limiting step would change from the dissociative adsorption of oxygen on the surface of molten oxide in the initial stage of reaction to the mass transfer of oxide ion from the surface to the inside of molten oxide in the following stage. Based on the kinetic analysis of the oxygen exchange process, C0_2 dissociation rate constant, CO_2 re-formation rate constant and the mass transfer coefficient of oxide ion in molten oxides were calculated for the FeO_x-CaO and FeO_x-SiO_2 systems. Addition of CaO and SiO_2 to molten oxide increases and decreases the oxygen exchange reaction rate, respectively.
2007-05-01