[boswell] catalysis OF HYDROGENATION BY NICKEL 19 



i.e. nickel carrying positive and negative hydrogens on the surface of 

 the particles. It might be desirable to restrict the term 'adsorbed 

 hydrogen' to this complex carrying hydrogen alone. 



The apparatus was now filled with nitrogen. On now heating 

 the catalyst at 400°C. with oxj^gen for four hours, only 50 c.c. of 

 oxygen disappeared. This indicates a marked difference between 

 this nickel and nickel prepared by reduction at 275°. 



The above catalyst was now reduced at 275° for seven days and 

 its activity determined with a mixture of ethylene and hydrogen in 

 the manner already described. No action occurred up to 120°C., 

 when a slight reduction in volum.e took place after passing the gases 

 for If hours. A gas analysis showed, however, no formation of 

 ethane. At 150° reaction set in very slowly. It required one hour 

 to accomplish the union of 100 c.c. hydrogen v/ith 100 c.c. of ethylene. 



Thus the original reduction at 400° rendered the catalyst very 

 much less active than the normal catalyst prepared at 275°. It 

 took up oxygen with difficulty, and in small amount, and upon 

 reduction of this oxidized nickel at 275° gave a catalyst with still a 

 very low activity. The complete removal of oxygen at 400° evidently 

 caused a marked alternation of the nickel, and when the catalyst in 

 this condition does catalyse the hydrogénation of ethylene it does so 

 by a mechanism quite different from the normal mechanism already 

 described. 



Experiment 11. 



The object of this experiment was to determine whether nickel 

 oxide, partially reduced at 275°, can be made to react with ethylene 

 in the absence of free hydrogen at any temperature up to 400°. 



The catalyst was prepared as in experiment 10, hydrogen being 

 passed for one hour at 275°. After cooling and displacing the hydro- 

 gen with nitrogen, ethylene was passed back and forth at gradually 

 increasing temperature of catalyst up to 400°. Gas analysis showed 

 that both ethane and hydrogen were formed. Thus, ethylene can 

 be made to react with the catalyser in the absence of free hydrogen, 

 but the action is abnormal, involving not only the hydrogénation of 

 ethylene but the liberation of free hydrogen. 



Experiment 12. 



Sabatierand Senderens (10), andalsoKelber(ll),havingobserved 

 that access of air to the catalyser diminishes or inhibits its activity 

 it was deisrable to determine the extent to which oxygen is taken up 

 by a normal catalyser at various temperatures. A catalyst was 

 prepared by reducing three grams of nickel oxide on asbestos at 



