Thermodynamic consistency of surface reaction mechanisms and its consequences for steady-state solutions

A major concern of elementary-step surface reaction mechanisms is the large number of rate parameters to be determined, which however cannot be chosen independently. The resulting surface reactions mechanism must fulfil thermodynamic consistency to yield meaningful results. Here, we present an algorithm implemented in the software DETCHEMADJUST in full detail. The proposed thermodynamic data is then applied to derive a mathematical scheme to describe the steady-state surface coverages. The scheme delivers an explanation for the occurrence of multiple solutions when calculating steady-state surface coverages for given temperature and gas-phase concentration. It offers a new path for numerical modelling of the steady-state behaviour of catalytic reactors such as emission control devices.