Enhanced low-temperature NH3-SCR performance by g-C3N4 modified Ce-OMS-2 catalyst

Abstract

The xCN/Ce-OMS-2 (x is the nominal weight percentages of g-C3N4, x = 5.0, 10.0, and 15.0 wt%) catalysts were prepared via an in-situ synthesis method. Physicochemical properties of the as-prepared materials were measured by means of the XRD, TEM, SEM, BET, XPS, H2-TPR, NH3-TPD, and in-situ DRIFTS techniques, and their catalytic activities for the selective catalytic reduction of NOx with NH3 (NH3-SCR) at low temperatures were evaluated. Among all the catalysts, the 10CN/Ce-OMS-2 catalyst showed the widest temperature span for NH3-SCR reaction and the best resistance to SO2 poisoning. This may result from that the modification of g-C3N4 promoted the electron transfer in catalyst, not only increased the concentration of active Mn4+ species and chemisorbed oxygen species, but also improved the surface acidity of the catalyst. In-situ DRIFTS results further showed that the modification of g-C3N4 increased the amount of acid sites and enhanced the formation of NH3 or NO intermediates (i.e., monodentate and bidentate nitrate), which enhanced the reaction activity of the catalyst.