| 초록 |
The NOx has been a significant cause of environmental issues such as photochemical smog, acid rain, ozone depletion, fine particulate pollution (PM 2.5), and even global warming. A selective catalytic reduction (SCR) system has become one of the promising techniques to convert various nitrogen oxides (NOx) to harmless nitrogen (N2) and water (H2O) by using ammonia (NH3) as a reducing agent. The most common vanadium (V) oxide-based commercial catalysts have been utilized as industrial NH3-SCR catalysts because of their chemical & thermal stability, high N2 selectivity, and low activity for SO2 oxidation at a high operation temperature window (300–400°C). However, the high working temperature of V-based catalysts limits its applicability concerning industrial furnaces and energy-conserving features. Therefore, it is imperative to develop an environmentally friendly and low-temperature (＞250°C) NH3-SCR catalyst with decreased V content and good tolerance to SO2. In the gas-sensing experiment, we found that N-containing graphene materials attributed to more NOx species adsorption on the catalyst surface at low temperature while suppressing the SO2 adsorption. Inspired by a gas-sensing experiment, we demonstrate a facile strategy for vanadate-based catalysts having high NOx conversion efficiency (＞90% @ 200°C) and improved SO2 resistance by impregnating ~3nm-sized N-doped graphene quantum dots (N-GQDs) to V2O5–WO3/TiO2 (4V-1W/TiO2) catalysts. The impregnation of 1wt.% N-GQDs possessed more surface acid sites and enhanced redox ability at low temperatures (200°C). Compared to the non-coated 4V-1W/TiO2 catalyst (67%), 1 wt% N-GQD-4V-1W/TiO2 catalyst exhibited more high De-NOx efficiency of ＞90% at low temperature (200°C). The strong redox interaction and facile electron transfer could also restrain the formation of surface sulfate species with SO2 tolerance. |
