Synergistic effect of cobalt and niobium in Co3-Nb-Ox on performance of selective catalytic reduction of NO with NH3

Combining the redox properties of Co and the acid properties of Nb in a Co-3-Nb-O-x catalyst is shown to provide superior performance in the selective catalytic reduction of NO with NH3 (NH3-SCR). Co3O4 shows average activity, however, it exhibits a poor N-2 selectivity. Nb2O5 is not active for NH3-SCR. However, the mixed Co-3-Nb-O-x catalyst shows higher NO conversion and N-2 selectivity than the single Co3O4 and Nb2O5 catalysts at 100-300 degrees C. The results of temperature programmed reduction by H-2 and X-ray photoelectron (XP) spectra indicate that the addition of Nb changes the chemical states of Co and decreases the concentration of Co3+ and O-alpha, adjusting the activity for catalytic oxidation to a moderate level. This suppresses the formation of undesired N2O from the over-oxidation of NH3. Incorporation of Co and Nb into one solid synergistically couples their redox behavior and surface acidity, ensuring the high catalytic activity and N-2 selectivity in NH3-SCR.

Automated summary

Combining the redox properties of Co and the acid properties of Nb in a Co-3-Nb-O-x catalyst results in superior performance in NH3-selective catalytic reduction of NO. This synergistic effect enhances activity and N2 selectivity.