What is difference between hydrogenation and hydrogenolysis?
The key difference is that the former does not involve bond cleavage, but the latter does. Both are essentially catalytically driven reactions of organic molecules with hydrogen gas.
Hydrogenation refers to the reaction between a susbtance and molecular hydrogen
Hydrogenolysis refers to the breaking of a bond between two carbon atoms or between an atom of carbon and that of another element via reaction with hydrogen. Again, a catalyst is usually required. This process is the basis of hydrotreatment of base oil which is carried out in refineries.