NOx Reduction by NH3 in the Presence of K, Pb, and SO2 over SO42–-Modified V2O5/Fe2O3 Nanosheet Catalysts

Reducing the multiple poisoning effect of alkali, heavy metals, and SO2 over catalysts is still an intractable issue for the selective catalytic reduction of NOx with NH3. Herein, the SO42–-modified V2O5/Fe2O3 nanosheet catalysts have been initially demonstrated for NOx removal in the presence of K, Pb and SO2. Notably, this catalyst exhibits outstanding multiple resistance to K, Pb and SO2. The evolutions of poisoning progress and reaction pathways as a function of K, Pb and SO2 copoisoning have been particularly revealed. The fresh catalyst proceeds with the reaction between adsorbed NHx species with gaseous NO via the Eley–Rideal pathway. After K and Pb copoisoning, the reaction changes to the Langmuir–Hinshelwood pathway because K and Pb mainly bond on the inherent SO42– sites of catalysts, maintaining sufficient acidic sites and reducible active VOx sites. After K, Pb, and SO2 copoisoning, the newly formed SO42– could bond on K&Pb while still conducting the reaction via the Langmuir–Hinshelwood reaction pathway. This work sheds light on the multiple poisoning-resistant mechanisms and provides a rational strategy to inhibit the multiple poisoning resistance of catalysts applied in nonelectrical industries.