Electrochemical water-gas shift reaction eWGSR

As evident from Eqns (15.8) and (15.9), when electrons are produced in an electrochemical reaction (i.e., Vpe > 0) as in the electrochemical water-gas shift reaction (eWGSR), the forward rate constant increases, the reverse rate constant decreases, and the equilibrium constant, being the ratio of the two, increases dramatically with an increase in potential. As a result, the equilibrium CO levels for eWGSR are lower than those for the conventional (thermal) WGS reaction. In other words, even if WGS catalysts could be found that are adequately active at lower temperatures, the thermodynamics of eWGSR are far more favorable in achieving lower levels of CO in H2. 

Figure 15.19 A schematic of the electrochemical water gas—shift reaction (eWGSR), in which A = anode, E = electrol3he, and C = cathode.

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