Synergistic effect of oxygen-containing and nitrogen-containing groups on promoting low-temperature denitration over non-metallic carbon-based catalyst

Abstract

Oxygen-containing and nitrogen-containing groups on the surface of non-metallic carbon-based catalysts have been regarded as active sites for NH3 selective catalytic reduction (NH3-SCR) of nitrogen oxides (NOx) at low temperature. In this study, series of AC-xO-yN catalysts were prepared via grafting oxygen-containing and/or nitrogen-containing groups on active carbon (AC). The activity test results showed that the denitration efficiency of AC-5O-0 N and AC-0O-4 N catalyst were only 20 and 44 % at a temperature of 120 °C and a GHSV of 4500 h−1, respectively, while the activity of the AC-5O-4 N catalysts reached 97 % at the same condition, indicating that the oxygen-containing and nitrogen-containing groups exhibited a superior synergistic effect in facilitating the low-temperature NH3-SCR denitration reaction. Characterization results revealed that the oxygen-containing groups (mainly carboxyl and lactone groups) contribute to NH3 adsorption and activation, while the nitrogen-containing groups (especially pyridine nitrogen groups) could promote NO adsorption and oxidation. The co-existence of oxygen-containing and nitrogen-containing groups can synergistically advance the low-temperature NH3-SCR denitration reaction on the surface of the AC catalyst via a fast SCR route. This work might provide insight into designing and preparing non-metallic carbon-based catalysts with high denitration performance.