3367.     TEMKIN, M., AND KIPERMAN, S.  [Kinetics of Synthesis and Decomposition of Ammonia on Various Catalysts.]  Jour. Phys. Chem. (U.S.S.R.) (in Russian), vol. 21, 1947, pp. 927-952; Chem. Abs., vol. 42, 1948, p. 2501.

        Equation for the rate v of reaction v=k1P1(P32/P23)a-k2(P23)1-a, in which P1, P2, and P3 are the partial pressures of N2, H2, and NH3, respectively, and k1, k2, and a are constant.  The energy of activation is expressed as a function of a.  The best composition of the gas mixture is given by P2:P1=3a.  The above equation is valid only when the system is not too far removed from the equilibrium state.  Variations of the adsorbed amount of N2 may cause the decomposition of NH3 to be a zero-order reaction at very low NH3 concentrations.  Considerations of earlier experiments shows that he equation is valid for various catalysts (Fe, Mo, W, U, Ce, Mn, Os, Ru, Cu, and Pt), that a usually is 0.5 and that the activation energy is almost independent of the nature of the catalyst.  This proves that the reaction mechanism is identical on various catalysts.  The rate of synthesis should depend on the degree of uniformity of the catalyst surface.  57 refs.