The water-gas shift reaction (WGSR) is a reversible slightly exothermic chemical reaction to convert carbon monoxide into hydrogen.
CO + H2O ↔ CO2 + H2
The exothermic essence of such reaction indicates that it is desirable to perform the water gas shift reaction at lower temperatures to obtain high CO conversion. However, to achieve sufficiently high reaction rates, it is necessary to operate at higher temperatures, even though the equilibrium composition is not so favorable under such conditions. In high temperature shift reactors, the WGSR takes place inside an adiabatic reactor loaded with small tablets of an Iron/Chromium based catalyst promoted with copper oxide. The active phase of the catalyst is magnetite (the catalyst supplied in hematite which needs to be carefully reduced into magnetite during startup) promoted by copper. Copper incorporation into the catalyst structure, providing a good dispersion as well as small crystallite sizes, will significantly enhance the intrinsic catalytic activity and drive the reaction more closely to the thermodynamic equilibrium (low approach to equilibrium). Normally, through utilizing a proper catalyst and stable operating condition, CO molar composition will be reduced down to 2-4 (Dry Molar basis) at the reactor outlet.