3758a.     ZAĬDENMAN, I. A., AND KHOMYAKOV, K. G.  [Initial Stages of the Interaction of Carbon Monoxide and Hydrogen With Nickel Catalyst at the Temperatures of Synthesis of Gasoline.]  Doklady Akad. Nauk S.S.S.R., vol. 78, 1951, pp. 901-904; Chem. Abs., vol. 45, 1951, p. 8,336.

          Heat evolved on contact between CO or a mixture 1CO:1H2 and a skeleton Ni catalyst, by leaching Ni-Al, reduced by H2 2-4 hr. at 190-200 was determined in an Al calorimeter with a Pt resistance thermometer, accuracy 0.0005-0.001, in experiments at 180-185 in both flow and circulation systems.  With the aid of simultaneous measurements of the change of pressure, the heat was referred to 1 mole gas disappeared.  First contact of CO with a freshly prepared Ni catalyst evolved over 85 kcal. per mole gas disappeared.  This is considerably higher than the heat effects, per 1 mole gas disappearing, of any of the 5 possible reactions (I) 2CO→C+CO2, 42.9; (II) 2CO+3Ni→Ni3C+CO2, 31.7; (III) 2CO+2H2→CH4+CO2, 30.15; (IV) CO+3H2→CH4+H2O, 16.9; (V) 3NI+CO+H2→Ni3C+H2O, 11.1 kcal.  The abnormally high initial heat effect of 85 kcal. can be attributed only to a change within the catalyst itself, specifically to partial recalescence.  On consecutive admissions of CO, each time after reduction of the catalyst with H2, the heat effect drops to and remains constant at about 34 kcal. per mole gas disappeared.  This corresponds to the carbide-formation reaction (II); reaction (V) is excluded, as there is no H2O formation with CO alone.  The rate of reaction (II) passes through a maximum within the 1st few minutes.  Its activation energy in the range 165-195 is 15.8 kcal. per mole.  the same heat effect, 34 kcal. per mole gas disappeared, is found in contact with a 1CO:1H2 mixture, on a catalyst previously exposed to CO.  This again is evidence for the occurrence of reaction (II); reaction (III) is out of the question, as in this instance one does observe formation of H2O; furthermore, subsequent admission of H2 alone produces hydrocarbons, which is proof that Ni carbide has been formed.  On more prolonged contact with the gas mixture, the heat effect decreases gradually, which indicates beginning occurrence of reaction (IV).  However, in the initial stage, the preponderance reaction is (II).

        ZAMRZLA, E.  See abs. 3187.

        ZARAKOVSKAYA, A. I.  See abs. 3763, 3764.