The production of dihydrogen obtained from “Coal gasification” can be increased by reacting carbon monoxide of syn gas mixture with steam in the presence of iron chromate catalyst.
CO(g) + H2O(g) \(\underset{Catalyst}{\stackrel{673k}{\rightarrow}}\) CO2(g) + H2O(g)
This reaction is called water gas shift reaction. CO2 is removed by scrubbing with sodium arsenite solution.