Study on the Reactivity of Adsorbed Hydrogen by means of Tritium as Tracer

Abstract

The relation between the bond strength of adsorbed hydrogen and the reactivity of the hydrogen for ethylene was investigated by using tritium as tracer. Hydrogen (or tritium) was adsorbed first on a powdered nickel at -78°C and tritium (or hydrogen) was subsequently adsorbed, then ethylene was added. The adsorption of hydrogen was made by changing thecoverage, i.e., 0.08 and 0.2 for the nickel reduced at 200°C, and 0.03 and 0.2 for the nickel reduced at 400°C. After a certain time, hydrogen and the mixture of ethane and ethylene were drawn off successively from the reaction vessel and separated. The assay of tritium in each fraction of gas was then made. The result on the nickel reduced at 200°C indicated that neither the hydrogen very strongly adsorbed nor that weakly adsorbed reacts with ethylene. The result on the nickel reduced at 400°C indicated that the hydrogen weakly adsorbed does not react with ethylene. These results suggest that the very strong sites for the adsorption of hydrogen, which are inactive for the hydrogenation reaction would diminish by the elevation of the reduction temperature.