A superior CeO2 @TiO2 catalyst with high dispersion of CeO2 for selective catalytic reduction of NOx with NH3

Abstract

NOx emissions have raised many environmental problems and posed a serious threat to human health. Development of excellent catalysts for selective catalytic reduction of NOx by NH3 (NH3-SCR) is desirable. In this study, by ingeniously encapsulating Ce ions into MIL-125 channels, CeO2 @TiO2 catalysts were prepared by annealing the Ce/MIL-125 precursor. Due to the porous framework structure of the MIL-125, a large amount of Ce ions were adsorbed into the pores, thus achieving high dispersion of CeO2 in the composites. All the CeO2 @TiO2 catalysts exhibit a NO conversion of nearly 100% at 350 ℃ and a wide temperature range larger than 200 ℃. The CeO2 @TiO2 (2/3) catalyst shows high specific surface area and porous structure. Meanwhile, a large amount of Ce3+ sites, enriched surface oxygen species, outstanding adsorption of NOx species and high surface acidity for CeO2 @TiO2 (2/3) catalyst account for the excellent NH3-SCR properties with a wide temperature range (200 ℃ ∼ 450 ℃) and excellent H2O and SO2 resistance.