Structure-Activity Relationship of Iron Titanate Catalysts in the Selective Catalytic Reduction of NOx with NH3

A series of iron titanate catalysts, FeaTibOx, with different Fe-Ti molar ratios are synthesized via a facile coprecipitation method and tested for the selective catalytic reduction (SCR) of NOx with NH3. The structural properties and redox behavior of the serial catalysts are comprehensively characterized. Comparing with pristine TiO2 and Fe2O3, the coexistence of iron and titanium species is favorable to form crystallites with specific Fe-O-Ti structure, Which is highly active for the NH3-SCR reaction. Fe4Ti4Ox catalyst with a Fe-Ti molar ratio of 1:1 shows the highest intrinsic activity, due to its smallest particle size, enhanced oxidative ability of Fe3+, highest mobility of lattice oxygen, and abundant acid sites. The correlation between catalytic performance and reactant adsorption capability/conformation is also studied, indicating that an appropriate method to improve the low temperature SCR activity of iron titanate catalyst is to enhance the adsorption ability of NOx as monodentate nitrate on catalyst surface.