Question

What is difference between hydrogenation and hydrogenolysis?

Answer 1

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.

Explanation:

Hydrogenation refers to the reaction between a susbtance and molecular hydrogen `H_2`. The substance could be, for example, an organic compound such as an olefin, which is being saturated (ethylene --> ethane), or could be substance undergoing reduction. The process usually takes place in the presence of a calalyst (e.g. palladium on graphite).

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.