Spectroscopic study of the ammonia-CO and pyridine-CO interaction on MgO-CoO solid solutions

Ammonia and pyridine (Py) are adsorbed both dissociatively and nondissociatively on dilute MgOCoO solid solutions. As on pure MgO, the dissociative process occurs mainly on cobalt-free parts of the surface, with formation of NH2- and bipyridyl and pyridine radical anions. Radical species formed in the proximity of Co2+ ions are oxidized to neutral bipyridyl. The interaction of CO with NH2- and molecularly adsorbed NH3 gives adsorbed HCONH- species, preferentially located on the MgO matrix. HCONH- species located in the proximity of Co2+ ions are oxidized to NCO- with simultaneous formation of Co(CO)4- species. A similar redox process occurs with Py, with formation of neutral bipyridyl and Co(CO)4-