$\mathrm{CO}$ is oxidised to ${\mathrm{CO}}_{\mathrm{2}}$ with steam in the presence of a catalyst, followed by the dissolution of ${\mathrm{CO}}_{\mathrm{2}}$ in water under pressure.

$\underset{\mathrm{water} \mathrm{gas}}{\mathrm{CO}+{\mathrm{H}}_2}+\underset{\mathrm{steam}}{{\mathrm{H}}_2\mathrm{O}}\stackrel{\mathrm{catlayst}}{\to }{\mathrm{CO}}_2+2{\mathrm{H}}_2$

And,

$\mathrm{CO} \& {\mathrm{H}}_2$ are not fractionally separated by using the differences in their densities. Carbon monoxide is separated from hydrogen gas by passing it through water at a pressure of $30$ atmospheres due to which carbon monoxide is absorbed in water unlike hydrogen gas

$\mathrm{CO}$ is not removed by absorption in aqueous ${\mathrm{Cu}}_2{\mathrm{Cl}}_2$ solution.

${\mathrm{H}}_2$ is not removed through occlusion with $\mathrm{Pd}$