Effect of water-gas shift reaction on reduction of iron oxide powder packed bed with H2-CO mixtures

Although the hydrogen reduction is thermally more disadvantageous than the CO reduction, it is advantageous that the reduction rate with H-2 is much larger than that with CO. In order to examine the effective use of hydrogen, the reduction of FeO1.05 powder packed bed with H-2-CO mixture was conducted, and the results were analyzed by a proposed model. The temperature, at which the reduction equilibria of FeO1.05 with H-2 and CO equal, is determined to be 1 093 K from the present results. The apparent rate constants are determined to be 33, 8.6 and 15 for the reduction of FeO1.05 with H-2, CO and H-2-CO mixture ((V) over bar (H2):(V) over bar (CO)=1 : 1), respectively. In the proposed model, when the water-gas shift reaction is taken into account, the additivity is established on the dependence of the rate constant of the reaction on the gas composition. When the water-gas shift reaction is not taken into account, the rate constant deviates negatively from the additivity. The apparent rate constants of the reduction determined in the present study take the middle values, and the contribution of the water-gas shift reaction is estimated to be 3% against its equilibrium. In reducing FeO1.05,with CO, the time when the sample is perfectly reduced is shortened by adding a small amount of H-2 and the rate enhancement effect of H, on the gaseous reduction remarkably appears at 1 093 K. The effect originates in the proceeding of the water-gas shift reaction.