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

Abstract

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-NH 3 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 CO 2 . As the most efficient active components, oxides of V, Mn, Fe and Cu were found. H 2 O leads to the decrease of activity but for some catalysts additionally to the increase in selectivity. The understanding of SO 2 influence needs more experimental data. There still are several open questions concerning more detailed mechanistic studies, and especially the role of nitrogen functionalities, H 2 O and SO 2 .

Influence of the nature and environment of manganese in Mn-BEA zeolites on NO conversion in selective catalytic reduction with ammonia

“…Among the proposed new catalysts are manganese containing materials because of their high reactivity already below 425 K [6][7][8][9] . The literature data shows that advantageous catalysts in SCR of NO at low temperature are manganese oxides supported on TiO2 10,11 and Al-SBA-15 12 as well as Mncontaining activated carbons 13 . However, their stability and/or selectivity to the desired products were not beneficial over 575 K, the use of catalysts in a wider temperature range is crucial for automotive NH3-SCR system.…”

Investigation of Low-Temperature Selective Catalytic Reduction of NOx with Ammonia over Mn-Modified Fe2O3/AC Catalysts

“…Catalyst 24 and modified activated carbon, [25][26][27] are also very important for SCR performance at low temperature due to their high surface areas and thermal stabilities, which can help the active substance become highly dispersed. Among them, carbon materials have attracted much attention due to their well-developed pore structure, high surface area and low price.…”

The application of modified cenospheres in DeNOx process

“…The latter are particularly harmful for both people and environment, and the amount of emitted NOx are regulated by the Directive of the European Parliament and of the Council of 14 December 2016 on the reduction of national emissions of certain atmospheric pollutants [1]. In order to reduce NOx emissions from power plants and industrial boilers, apart from primary methods, whose effectiveness is not sufficient, additional technologies are used [2][3][4][5][6]: SCR (selective catalytic reduction), SNCR (selective non-catalytic reduction) and hybrid technologies SNCR-SCR. SCR is the most effective method of removing NOx from flue gases, but requires a suitable catalyst.…”