3051.     SCHENCK, R., KRÄGELOH, F., AND EISENSTECKEN, F.  [Equilibria in the Reduction, Oxidation, and Carburization of Iron.  II.  Methane-Hydrogen Equilibria in the Presence of Cobalt.]  Ztschr. anorg. Chem., vol. 164, 1927, pp. 313-325; Chem. Abs., vol. 21, 1927, p. 3799.

        Authors wish to show whether the equilibrium conditions resulting from the action of Co upon CO are solely those due to the reaction (1) 2 CO=C+CO₂, or whether other equilibria involving a Co carbide also must be considered.  The results of an incomplete series of experiments performed in 1914 are given.  At that time, Co was considered to act solely as a catalyst in the reaction mentioned above and no carbide equilibria were thought to be involved.  Doubt in the matter has led the authors to determine the equilibrium conditions in the closely related system CH₄=C+2 H₂ catalyzed by Co.  The procedure is the same as that used in the system Fe-CH₄ (abs. 3050).  The primary reaction is a catalytic decomposition of the CO according to (I).  Co is a better catalyst for this reaction than involving Co carbide.  This equilibrium is reached more slowly than the former.  Both equilibria are studied quantitatively over the range 310°-740°.  Above 680°, the reaction involving the carbide is no longer encountered.  Although Co carbide was not isolated, its properties are predicted.  The parallelism between the effect s of Fe₃C and Co carbide on the decomposition of CH₄ leads the authors to believe that, as with Fe, it is likely that Co carbide forms mixed crystals with Co.  The heat of formation of Co carbide is found by calculation to be -11,300 cal.  The authors draw the following conclusions with regard to the influence of Co upon equilibrium (I):  Above 668° the influence is purely catalytic; below this temperature it is difficult to explain the equilibrium relations unless the existence of dilute mixed crystals of Co carbide in Co is postulated.