Heat Decomposition of Prussian Blue and Iron Cabide Formation

Abstract

In order to produce iron carbide industrially, heat decomposed products of prussian blue were investigated by means of X-ray diffraction and chemical analysis.
The decomposition was performed at 973∼1173 K under the three kinds of atomsphere of nitrogen, carbon dioxide and their mixture in the experimental apparatus. Fe₃C could be produced by the decomposition of the industrial grade of prussian blue in N₂ atmosphere at higher temperature. The yield of Fe₃C increased with increasing temperature, especially above 1073 K duration of the decomposition.
The lattice constans of Fe₃C formed at 1073 K for 1.8 ks decomposition were a=0.45211 nm, b=0.50902 nm, c=0.67439 nm.
Prussian blue decomposed to Fe₃C or mixture of Fe₃C, Fe and FeO in CO₂ atmosphere.
The composition of the products chiefly depended on the decomposing conditions and the flow rate of CO₂.
Cabon dioxide in the mixed atmosphere had less influence on the oxidation to prussian blue than that of the oxidation in CO₂.
This fact is caused by the lower partial pressure of CO₂ in the mixed atmosphere than that in CO₂.