3179.     SHUĬKIN, N. I., MINACHEV, K. M., AND ROZHDESTVENSKAYA, I. D.  [Hydrogenation and Dehydrogenation of Hydrocarbons With Low-Percent Nickel Catalysts.]  Doklady Akad. Nauk S.S.S.R., vol. 72, 1950, pp. 911-913; Chem. Abs., vol. 44, 1950, p. 8332.

        Catalysts with Ni contents of 0.125-4% were prepared by 40-45 min. impregnation at 30°-35° of 1 gm. activated charcoal with 2 ml. solution of Ni(NO₃)₂, drying at 125°, and reduction in H₂ at 330°.  Hydrogenation (I) of C₆H₆ was carried out in a stream of excess H₂ at 115°-176°, space velocity 0.025-0.2 l. per l. catalyst per hr.; dehydrogenation (II) of cyclohexane at 300°-302°, space velocity 0.2.  (I) proceeds to a significant extent with catalysts containing 1% Ni or more; the reaction is just barely noticeable with 0.5% Ni.  In (II), the initial activity of the catalyst varies very little with the Ni content, varying from 0.5-4%; with the progress of the reaction, the activity of the catalysts falls rapidly, by a factor of 3-4 after 2,000 min.  In reaction (I), the degree of hydrogenation is virtually independent of the temperature at 120°-176° and is not affected by a variation of the space velocity by a factor of 4; under these conditions, it attains 100%.  Further increase of the space velocity, by a factor of 8, lowers the degree of hydrogenation 68-70%.  At constant space velocity of 0.06, the activity of the 4% Ni catalyst maintains itself at a near 100% level for more than 25 hr., and that of the 2% catalyst falls off only slowly.