Effect of Fe²⁺/Fe³⁺ Ratio on the Reduction Behavior of SFCA-I in Hydrogen-enriched Atmosphere

Abstract

In this study, the influence of Fe²⁺/Fe³⁺ ratios in SFCA-I on its reducibility are examined. Five types of powder samples containing SFCA-I with different Fe²⁺/Fe³⁺ ratios were prepared using chemical reagents by solid phase reaction at high temperature. The samples were heated up to 800°C in the different atmospheres of CO–CO₂–H₂–H₂O systems. The reducibility of the samples was evaluated using the integrated intensity ratio identified by XRD before and during the reduction experiment.

The integrated intensity ratio of SFCA-I is not decreased up to 700°C in CO–CO₂ atmosphere, whereas the intensity become weak in CO–CO₂–H₂–H₂O atmosphere. The integrated intensity ratio of SFCA-I remains at 800°C under CO–CO₂ atmosphere. On the other hands, the integrated intensity ratio disappears under the CO–CO₂–H₂–H₂O atmosphere. The increase in the Fe²⁺/Fe³⁺ ratio in SFCA-I leads to the increase in the concentration of Fe in SFCA-I and significant decrease the integrated intensity under different reducing gas conditions at 750°C. The increase in the amount of Fe²⁺ may lead to enter Fe²⁺ into the spinel unit, and this may contribute to the reduction of SFCA-I.