2011 Volume 51 Issue 8 Pages 1204-1212
It is widely known that the direct contact between solid carbon and iron oxide shows quite a fast reduction rate in comparison with CO gas reduction. However, it is difficult to sustain the physical contact between solid carbon and iron oxide. Furthermore, the contact mode will be different from the production method, which will affect the reaction kinetics strongly.
In this study, different kinds of contacts between solid carbon and hematite were made to clarify the reaction mechanism. One contact mode is the deposition of the carbon layer on the hematite surface using a vacuum evaporation method. Another method is the implantation of carbon ions into hematite. Using XPS (X-ray photoelectron spectroscopy), the binding energy of Fe–O–C was measured. Heating under an argon atmosphere was carried out. Both samples showed quite different reaction behavior, though the temperature at the beginning of the reduction reaction was almost the same. From these results, it was determined that the position of carbon will change the reaction behavior drastically, because it is important how the CO gas escapes from the reaction site.