For the simultaneous equilibrium of NH3 synthesis and sorption, no experimental data could be obtained for validation of the model. Thus, the NH3 partial pressure as obtained from the GEM model is compared to the NH3 equilibrium pressure calculated from experimental data for the sorption equilibrium constant 33 in Figure In summary, it is possible to calculate the NH3 synthesis equilibrium by both the stoichiometric and the GEM method, but the latter is in better accordance with experimental data, especially at higher pressures. Since this method can also describe the NH3 sorption equilibrium to a sufficient extent once the missing thermodynamic data is fitted, GEM is chosen as the method of choice for equilibrium calculations throughout this work.