3504.     ---------------.  [TUTIYA, H.]  Catalytic Decomposition of Carbon Monoxide.  III.  Behavior of Iron Carbides.  Bull. Inst. Phys. Chem. Research (Tokyo), vol. 10, 1951, pp. 556-562, abs. 58-59 (in English); Sci. Papers Inst. Phys. Chem. Research (Tokyo), vol. 16, No. 306-309, 1931; Chem. Abs., vol. 25, 1931, p. 5615.

        In the catalytic decomposition of CO by Fe₃O₄ or Fe₃C, some relations between percarbide (Fe_χC), cementite, and free C were determined.  At 270°-320° Fe₃O₄ is reduced to Fe_χC, and no FeO, Fe, or Fe₃C is found in the course of this reduction, which indicates equilibrium exists between Fe₃O₄ and Fe_χC in the solid phase and between CO and CO₂ in the gaseous phase.  Reduction at 280°-320° gives a mixture of Fe_χC and Fe₃C and the amount of the latter increases with rise in reaction temperature.  At 450°, Fe_χC decomposes rapidly into Fe₃C and C.  At 270°, Fe_χC is formed not only from Fe and its oxides but from Fe₃C.