Promotional role of Mo on Ce0.3FeOx catalyst towards enhanced NH3-SCR catalytic performance and SO2 resistance

Abstract

The SO2 resistance of low temperature NH3-SCR in non-electric power industries has always been the bottleneck of this technology. Herein, a series of Mo-modified Ce0.3FeOx catalysts (MoaCe0.3FeOx) were synthesized by an easy to scale-up, environment-friendly two-step solid interface reaction and applied to the treatment of flue gas from the glass industry. Incorporation of Mo into Ce0.3FeOx catalyst could not only remarkably expand the operation temperature window in both low and high temperature regions, but also maintain high catalytic activity (>85% NOx conversion) under 65 h long stability test conditions even with the coexistence of H2O and SO2. The two-step interface reaction over MoaCe0.3FeOx provided an increased specific surface area and more amorphous structure, forming highly dispersed MoO3 species on the surface of the catalyst which serves as a sacrificial site to react with SO2. The process of redox reaction has been greatly improved due to the facilitated electron transfer between Fe2+ and Ce4+ as well as more oxygen vacancies and active oxygen. The enhanced presence of NH4+ could react with gaseous NO species via Eley–Rideal (E–R) mechanism due to the lack of nitrate species (greatly inhibited) while the NH4NO3 was not generated during the reaction which is responsible for excellent low temperature SCR performance as well as high N2 selectivity. Furthermore, less sulfate species and no bulk sulfate were formed, which indicated that the doping of Mo could effectively reduce the basic sites and delay the irreversible deactivation as well as reduce catalyst sulphation. The above features provide a strategy for design and development of non-vanadium-based catalysts with low temperature SO2 resistance in non-electric power industries with high NOx emission concentrations.