Influence of copper doping on the low-medium NH3-SCR activity of magnetic W/Fe2O3 catalyst: Its synergetic effect of glucose dosage

Abstract

Herein, in order to investigate the influence of copper doping and glucose dosage on the NH3-SCR activity of tungsten-impregnated 7.5W/Fe2O3 catalyst, four kinds of magnetic Fe2O3 and Fe2CuOz supports were fabricated via the solution combustion coupled with the chemical oxidization of hydrogen peroxide by keeping the glucose/urea molar ratio being 5:20 and 10:20, respectively. The enhancement of glucose/urea molar ratio from 5:20 to 10:20 helps to enrich the pore structure of magnetic Fe2O3 support and enlarges its BET surface area effectively, which is unhelpful to the thermal-stability of γ-Fe2O3 crystal during the calcination at 400 °C even if tungsten species were impregnated on its surface, thus decreases the NH3-SCR activity of magnetic 7.5W/Fe2O3-GC:UA=5:20. However, the doping of copper hinders the growth of γ-Fe2O3 crystal and prevents the formation of α-Fe2O3 crystal of magnetic 7.5W/Fe2O3-GC:UA=10:20 effectively, although it decreases the BET surface area of Fe2O3 supports sharply. Furthermore, the doping of copper promotes the formation of high dispersive CuFe2O4 and induces the reaction of Cu2++Fe2+↔Cu++Fe3+ in magnetic 7.5W/Fe2O3 catalysts, thereby improves their surface Oα/(Oα+Oβ) molar ratios and redox properties. Magnetic 7.5W/Fe2CuOz-GC:UA=10:20 catalyst presents the best low-temperature redox properties or/and NH3-SCR activity with high surface concentrations of Cu+ and Fe3+ species, and there exists a synergetic effect of copper doping and glucose dosage on the NH3-SCR activity and the physical-chemical properties of magnetic 7.5W/Fe2O3 catalyst.