Enhanced SO2 tolerance of FeCeOx/CNTs catalyst for NO and Hg0 removal by coating shell SiO2

Abstract

Majority of catalysts for simultaneous removal of NO and Hg0 from coal-fired flue gas generally suffered from the deactivation by SO2. In this work, a facile method was developed for controllable synthesis of SiO2@FeOx-CeOx/CNTs (noted as SiO2@FeCeOx/CNTs) catalyst with a unique core-shell construction for DeNOx and Hg0 removal in the flue gas with the presence of SO2. The prepared SiO2@FeCeOx/CNTs exhibited high stability and excellent SO2 tolerance. Although the addition of 500 ppm SO2 has a little adverse influence on the catalytic activity of SiO2@FeCeOx/CNTs, its NO and Hg0 removal efficiencies remained (89.52 ± 2.01)% and (82.73 ± 2.04)% at 240C and 30,000 h−1, which are (15.44 ± 2.86) and (16.13 ± 2.86) percentage points higher than uncoated FeCeOx/CNTs. It can be observed that large amounts of crystal FeSO4, amorphous ammonium sulfate and ammonium sulfite formed on the spent FeCeOx/CNTs. For the SiO2@FeCeOx/CNTs core-shell catalyst, the coated SiO2 shell establish an available barrier to hinder the generation of FeSO4 and restrain the reduction of chemisorbed oxygen, improving its stability and SO2 tolerance. Therefore the core-shell structure is a feasible way to develop the SO2 tolerance catalysts during the simultaneous NH3-SCR and removal of Hg0.