Magnetic iron-cerium-tungsten mixed oxide pellets prepared through critic acid sol-gel process assisted by microwave irradiation for selective catalytic reduction of NOx with NH3

Abstract

The performance over a series of iron-cerium-tungsten mixed oxide catalysts were investigated for selective catalytic reduction (SCR) of NOx with NH3. These catalysts were prepared through critic acid sol-gel process assisted by microwave irradiation, which is a sample, time-saving and economic method to obtain magnetic iron-based catalyst compared with the traditional hydrothermal treatment assistant critic acid sol-gel method. X-ray diffraction (XRD), N2 absorption-desorption, X-ray photoelectron spectroscopy (XPS), Temperature programmed reduction (H2-TPR) and Temperature programmed desorption (NH3-TPD) were used to characterize the catalysts. The results showed that the addition of both cerium oxide and tungsten oxide improved the NH3-SCR activity of magnetic iron oxide. Higher calcination temperature enhanced the high-temperature catalytic activity of Fe0.85Ce0.10W0.05Oz, although might decrease its low-temperature NH3-SCR activity. The concentration of the surface adsorbed oxygen and the total oxygen were improved after introducing both cerium oxide and tungsten oxide compared with the addition of one auxiliary. This also depressed the formation of γ-Fe2O3 and α-Fe2O3 crystallite in magnetic iron oxide, and enhanced the dispersion of active elements on its surface, thereby improved its NH3-SCR activity.