[boswell] catalysis OF HYDROGENATION BY NICKEL 3 



due to occluded hydrogen, the order of activity being also the order 

 of capacity for occluding hydrogen. Fokin ascribes the activity of 

 nickel in hydrogénation to the occluded hydrogen which he believes 

 to exist in the meta' partly in the monatomic condition. 



Ipatiew (4) discovered that many organic compounds could be 

 reduced by hydrogen at high pressure using nickel oxide as catalyser 

 instead of reduced nickel. 



Bedford and Erdmann (5) prepared a nickel oxide in a very 

 finely divided and voluminous condition by igniting in a muffle a 

 concentrated aqueous solution of nickel nitrate mixed with sucrose. 

 The resulting mass, which Erdmann believes is nickel oxide, is said 

 to be more active than reduced nickel in effecting hydrogénations. 

 Erdmann expresses the opinion that the activity of reduced nickel 

 as ordinarily used in the hydrogénation process is due to the presence 

 of a sub-oxide of nickel. This contention has been combated by 

 Nermann (6) and others, and has given rise to an interesting contro- 

 versy which has resulted in the accumulation of considerable new data 

 regarding the relative activities of nickel oxide and reduced nickel in 

 hydrogénations, and the presence or absence of sub-oxide in reduced 

 nickel. No definite conclusions regarding the main point under 

 discussion, viz., whether metallic nicke- or an oxide of nickel is the 

 active agent, appears to have been reached. Later in this paper, the 

 reason for this confusion will be pointed out and the belief advanced 

 that it is neither metallic nickel nor nickel oxide that is active in 

 hydrogénations. 



The experimental data of this paper, together with the observa- 

 tions of other investigators, has led to the conclusion that nickel 

 oxide reduced by hydrogen at 275° to 300°C. consists, at the surface, 

 of elementary metal carrying a surface film of dissociated water in 

 the form of charged hydrogens and hydroxyls. This may be repre- 

 sented thus: 



(Ni) 



H+ 

 OH- 

 H+ 

 OH- 



As will be seen from the experimental data, the matter is 

 complicated by the fact that the reduction of all the NiO at 275° to 

 300°C. to form the above complex is very difificult. Even after ten 



