NO removal activity and surface characterization of activated carbon with oxidation modification

Abstract

Non-pitch coal-based activated carbon (NPAC), using a novel non-pitch binder, was used to inexpensively prepare oxidized activated carbon (NPAC-O0) by oxidation modification of oxygen-depleted. Using a fixed bed reactor and BET, FTIR and XPS techniques, this research investigated the denitrification rate, the changes in acidic/basic surface functional groups, and the mechanism of NOx removal. The results demonstrated that in the preparation of catalyst NPAC-O0, oxygen reacted with microcrystalline edges, defect parts and specific chemical functional groups adsorbed on the surface of NPAC to build and ream pores, such that the total pore volume increased by 30.26%. Additionally, the basic functional group content decreased by 36.42%, which was ascribed to a reduction in the pyridine-like and pyrrolic moieties, whereas the acidic functional group content increased by 128.7%, which was a result of the introduction of CO and OCO groups. The removal of NOx by oxidized activated carbon (NPAC-O0) involves both adsorption and catalytic conversion, where the acidic groups absorbed NH3 and the polar/basic functional groups absorbed O2 and NO enhancing the activated carbon activity. The NH3 adsorption is the critical step in the NH3NOO2 reaction. In the mechanism, the increased acidic CO groups promote chemical absorption of NH3 and assist in H-abstraction of NH3 to formation NH2, which then reacts with adsorbed NO2 or NO to generate N2 and H2O in the presence of oxygen. At 30 °C, the denitrification rate of NPAC-O0 remained at 79.46% after a 140 min reaction.