An iron catalyst is used in the Haber process in which gaseous ${\mathrm{N}}_2$ and ${\mathrm{H}}_2$ react to produce${\mathrm{NH}}_3$  What is the role of this catalyst?

In the Haber process, ammonia gas is obtained when gaseous ${\mathrm{N}}_2$ and ${\mathrm{H}}_2$ react. The reaction takes place as,

${\mathrm{N}}_{2\left(\mathrm{g}\right)}+3{\mathrm{H}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{NH}}_{3\left(\mathrm{g}\right)}$

Here, the catalyst used is an iron.

This iron catalyst interacts with ammonia (${\mathrm{NH}}_3$)