Sodium ion intercalation in vanadium oxide promotes low-temperature NH3-SCR activity: Sodium vanadium bronzes (Na0.33V2O5) for NOx removal

NH3-SCR (selective catalytic reduction) is a key technique for converting harmful NOx to harmless N2 and H2O in exhaust gases. Herein, V2O5, Na0.33V2O5 and Na1.2V3O8 are synthesized by a simple chemical process (the oxalate method) as examples of Na-intercalated vanadium oxide (sodium vanadium oxide bronze) for low-temperature NH3-SCR less than 150 degrees C. Among them, Na0.33V2O5 shows 92% (dry) and 86% (in the presence of 10 vol% water) NO conversions at 150 degrees C. The reaction rate of Na0.33V2O5 is 6.1-times higher than that of V2O5, indi-cating that Na intercalation accelerates NH3-SCR cycles. Mechanistic analysis suggests that the reaction mech-anism of Na0.33V2O5 is different from those of other V-based catalysts. Although it has been believed that alkali ions inhibit catalytic cycles of NH3-SCR, the results of this study suggest that alkali ions affect the structural, redox and adsorption properties of bulk V2O5, leading to an increase in NH3-SCR activity.