The influence of the modification of carbonaceous materials on their catalytic properties in SCR-NH3. A short review

Carbonaceous catalysts are promising materials for the low-temperature (< 523 K) process of NO reduction with ammonia. Based on literature and own experience of the authors, this review focuses on the possibilities to enhance their catalytic performance. It may be increased by the introduction of oxygen or nitrogen functionalities. So obtained materials may be used in SCR-NH₃ either as catalysts or supports for transition metals oxides/hydroxides. Oxygen functionalities increase activity only to a small extent, but are necessary to prepare an efficient MeO_x/AC catalyst. Nitrogen surface species lead to a considerable increase in DeNO_x activity, as well as stability towards their oxidation to CO₂. As the most efficient active components, oxides of V, Mn, Fe and Cu were found. H₂O leads to the decrease of activity but for some catalysts additionally to the increase in selectivity. The understanding of SO₂ influence needs more experimental data. There still are several open questions concerning more detailed mechanistic studies, and especially the role of nitrogen functionalities, H₂O and SO₂.