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