Deactivation Mechanism of Potassium on the V2O5/CeO2 Catalysts for SCR Reaction: Acidity, Reducibility and Adsorbed-NOx

• Published in: Environmental science & technology Vol. 48; no. 8; pp. 4515 - 4520
• Main Authors: Peng, Yue, Li, Junhua, Huang, Xu, Li, Xiang, Su, Wenkang, Sun, Xiaoxu, Wang, Dezhi, Hao, Jiming
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.04.2014
• Subjects: acidity; Acids - chemistry; Adsorption; ammonia; Applied sciences; Atmospheric pollution; Catalysis; catalysts; Cerium - chemistry; desorption; Exact sciences and technology; General processes of purification and dust removal; nitrates; nitric oxide; Nitric Oxide - analysis; Nitrogen Oxides - chemistry; oxidation; Oxidation-Reduction; poisoning; Pollution; potassium; Potassium - chemistry; Prevention and purification methods; Spectrophotometry, Infrared; Spectrum Analysis, Raman; Surface Properties; Temperature; Vanadium Compounds - chemistry; Nitrogen oxide; Catalyst poisoning; Pollution control; Nitrogen compounds; Cerium oxide; Reaction mechanism; Vanadium oxide; Air pollution; Physicochemical purification; Pollution abatement; Selective catalytic reduction; Flue gas purification; Potassium; Catalyst
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es405602a

A series of V2O5/CeO2 catalysts with different potassium loadings were prepared to investigate alkali deactivations for selective catalytic reduction of NOx with NH3. An alkali poisoning mechanism could be attributed to surface acidity, reducibility, and NOx adsorption/desorption behaviors. The detailed factors are as follows: (1) decrease of surface acidity suppresses NH3 adsorption by strong bonding of alkali to vanadia (major factor); (2) low reducibility prohibits NH3 activation and NO oxidation by formation bonding of alkali to vanadia and ceria (important factor); (3) active NOx(-) species at low temperature diminish because of coverage of alkali on the surfaces (minor factor); and (4) stable, inactive nitrate species at high temperature increase by generating new basic sites (important factor).