Reaction pathway? More adsorption of NH3/NH4
+ species and the higher reactivity with gaseous NO maintain the process of E−R reaction path, leading to a satisfactory SCR activity of K poisoned NbFeVOx/TiO2. Whereas the decreased adsorption and reactivity of NH3/NH4
+ and NOx restrains the process of L−H reaction path, thus showing inferior SCR activity of K poisoned FeVO4/TiO2.
FeVO4-based catalysts with a wide temperature window and high SO2 tolerance have attracted increasing attention for the selective catalytic reduction of NOx with NH3. However, the alkali-resistance of FeVO4-based catalysts is still challenging. In this study, the K-resistance of FeVO4/TiO2 was markedly improved via the Nb modification. It was demonstrated that the adsorption and reactivity of NH3/NH4
+ and NOx species on K poisoned FeVO4/TiO2 both decreased, which restrained the process of Langmuir-Hinshelwood reaction path. As a comparison, more adsorption of NH3/NH4
+ species and the higher reactivity with gaseous NO maintain the process of Eley-Rideal reaction path, leading to a satisifactory SCR activity. This work demonstrated an effective route to improve alkali-resistance via modulating reactivity and reaction path of adsorbed NH3/NH4
+ and NOx species over Nb modified vanadate catalysts, which presented a new point for the development of high-performance alkali-resistant SCR catalysts.Zum Volltext