The conversion of ${\text{CH}}_3\text{C}\equiv \text{CH}$ to ${\text{CH}}_3\text{CH}={\text{CH}}_2$ requires:

The conversion of propyne (${\text{CH}}_3\text{C}\equiv \text{CH}$, an alkyne) to propene (${\text{CH}}_3\text{CH}={\text{CH}}_2$, an alkene) is a partial hydrogenation reaction. This controlled reduction requires a poisoned palladium catalyst, commonly known as Lindlar's catalyst ($\text{Pd}/{\text{CaCO}}_3$ deactivated with lead or quinoline), to prevent over-reduction all the way to an alkane. Ordinary ${\text{H}}_2/\text{Pd}$ would reduce it completely to propane (${\text{CH}}_3{\text{CH}}_2{\text{CH}}_3$).