How can production of hydrogen from water gas be increased by using water gas shift reaction ?

Explanation

Water gas is produced when superheated steam is passed from over red hot coke or coal at 1270 K in presence of Ni as catalyst.
`underset("Coke")(C(s))+ underset("Steam")(H_(2)O(g)) underset(Ni)overset(1270K)to underset("Water gas")ubrace(CO(g) + H_(2)(g))-121.3 KJ`
It is difficult to obtain pure `H_(2)` from water gas since `CO` is difficult to remove. Therefore, to increase the production of `H_(2)` from water gas, CO is oxidised to `CO_(2)` by mixing it with more steam and passing the mixture over `FeCrO_(4)` catalyst at 673 K.
`underset("Water gas")ubrace(CO(g)+H_(2)O(g))+ underset("Steam")(H_(2)O(g)) +underset(FeCrO_(4))overset(673K)to CO_(2)(g) + 2H_(2)(g)`
This chemical reaction in which CO of water gas reacts with with steam of form `CO_(2)` and more `H_(2)` is called water gas shift reaction (WGSR).
`CO_(2)` from syngas thus produced can be removed either by scrubbing the mixture with sodium arsenite solution or by passing the mixture through water under 30 atm pressure when `CO_(2)` dissolves leaving behind `H_(2)` which is collected.