2. Computational details
The active site is modeled by a cluster with the formula M(OH)3(H2O)2, whereM = Fe, Co, Rh (see figure 1).
The model is further referred to as X. This cluster model represents some of the surface species that can be observed on
the metal oxide surface or in zeolite cavities.
All metals discussed here have an oxidation state III as one of the commonly encountered.
Although for Fe and Co the oxidation state II is often the initial one after the catalyst’s preparation, under reaction conditions in the absence of reducing agents (such as hydrocarbons) the oxidation state III should be considered as a reference.