2031.     LACHINOV, S. S.  [Reduction of Iron Catalysts Used in the Synthesis of Ammonia.  III.  Duration of the Complete Reduction of the Catalyst and Its Activity in Relation to Its Composition, the Regimen of Smelting and the Conditions of Reduction.]  Jour. Appl. Chem. (U.S.S.R.), vol. 10, 1937, pp. 1847-1866 (in French, pp. 1866-1867); Chem. Abs., vol. 32, 1938, p. 2298.

        All conditions of reduction that lead to the accumulation of H₂O vapor in the gas phase above the catalyst increase the duration of reduction and lower the catalytic activity.  The harmful action of H₂O vapor upon the activity of the catalyst is explained by the development of the oxidation-reduction processes, which caused the recrystallization of the contact surface.  An increase of the volume velocity of gas mixture decreases the duration of the reduction and increases the activity of catalyst, but only to a certain limit, after which, a further increase of the volume velocity has no effect.  The velocity of the reducing-gas stream at which H₂O vapor is removed as fast as formed permits reduction in the shortest time and produces the most active catalyst.  An increase of temperature, all other conditions being equal, decreases the duration of complete reduction of catalyst and lowers its activity, but increase of the volume velocity of gas mixture decreases the harmful effect of increased temperature.  An increase of pressure during the reduction lowers the activity, but an increase of the volume velocity decreases or completely neutralizes this effect.  A slight increase of temperature and duration of smelting of the catalyst increases the duration of reduction.  Oxidation of Fe under O₂ pressure with an admixture of activators yields a highly active and stable catalyst, in spite of the presence of 1.5% SiO₂.  The Fe-Mo catalyst, prepared from a ferromolybdate by oxidation smelting with the K₂O-Al₂O₃ admixture, is not easily reduced, and has an average activity and high stability.  Admixture of oxides of Cu or Ni to this catalyst decreases its activity.  40 refs.