Hydrogenation
Conversion of ethene to ethane is an example of addition of hydrogen. This reaction is carried out in the presence of Ni or pt or pd catalyst at 200−300∘C

CH2=CH2(g)

‌ Ethene ‌

+H2(g)

Ni∕Cd

─────▸

200−300∘C

CH3−CH3(g)

Ethane