The process of producing syngas or synthesis gas from coal is called coal gasification
C(s) + H2O(g) Ni 1270K -------> CO(g) +H2(g)
The production of hydrogen can be increased by reacting carbon monoxide of syngas with the steam in presence of iron chromate as catalyst at 673K. This is called water shift reaction
CO (g) +H2O (g) FeCrO4, 673K ---------> CO2 (g) +H2 (g)
The CO2 thus produced can be removed either by scrubbing with a solution of sodium arsenite or by passing the mixture through water under 30 atm. Pressure when CO2 dissolves leaving behind H2 which is collected.