The catalytic hydrogenation of ethylene on nickel-copper and nickel-gold alloys

Abstract

The rate of ethylene hydrogenation on copper-nickel alloy films in the temperature range 0 ° to 21 °C has been measured. The films were prepared by successive deposition of copper and nickel by the usual film-forming procedures followed by sintering the films in 5 cm of hydrogen at either 300 ° or 500 °C. The activity per unit area of film increases to a value 7 to 15 times as great for a catalyst containing 10% to 20% Cu as for pure nickel. Similarly, catalysts containing 5% to 20% nickel are as much as eight times as active as pure nickel. A minimum of activity with composition is found in the 25% to 35% nickel region, where the activity is about the same as on pure nickel. X-Ray data show that films homogenized by heating to 500 °C in a few cm of hydrogen form an alloy containing about 60% copper; the excess of nickel or copper present gives a diffraction pattern for the pure metal. Gold-nickel alloys containing 15% and 55% gold, respectively, have rates only about one-tenth as great as that of pure nickel. The apparent energies of activation for the reaction over the copper-nickel alloys vary with composition in the range 9 to 12 kcal/mole; those for the two gold-nickel alloys are about 4 kcal. The reaction rate is first order with respect to hydrogen and independent of ethylene for the copper-nickel alloys and for pure nickel; it is first order with respect to both hydrogen and ethylene for copper.