Materialographic Investigation on the Mechanism of Hydrogen Production through the Reaction between Iron Carbide and Steam at a Temperature of 673 K

Abstract

Materialographic investigation was applied to the microstructure evolution of iron carbide brought by the reaction with steam at 673 K in order to clarify the mechanism of hydrogen production through the iron carbide-steam reaction. Optical and scanning electron microscopy in combination with X-ray diffractometry revealed that a layer of iron oxide, mainly magnetite, forms on the external and internal surfaces of porous particles of iron carbide as a result of the direct oxidation of iron carbide. The oxide phase contains nano-sized graphite particles that are highly crystallized and dispersed uniformly in the oxide layer. The oxidation of iron carbide by steam was confirmed to be responsible for the hydrogen production at 673 K.