Ceria-tungsten-tin oxide catalysts with superior regeneration capacity after sulfur poisoning for NH3-SCR process

Nowadays, there exists a trade-off between high-temperature thermal stability and low-temperature catalytic activity for metal oxide catalysts for the NH3-SCR reaction, which restricts the practical application of metal oxide catalysts on diesel vehicles for NOx emission control. In this work, we systematically investigated the relationship between catalytic performance and thermal durability over a novel Ce-W-Sn ternary oxide (CeWSnOx) catalyst by varying the calcination temperature over the range 500-900 degrees C. Instead of thermal deactivation, the NH3-SCR performance of the CeWSnOx catalyst was significantly improved by roasting treatment at temperatures as high as 800 degrees C. Additionally, in situ SO2 poisoning led to the loss of the low-temperature activity for the optimized CeWSnOx-800 catalyst. The superior thermal stability of the CeWSnOx-800 catalyst and the poor thermal stability of the formed sulfates, however, made full thermal regeneration of the sulfur-poisoned catalyst feasible below 700 degrees C. The anti-sintering characteristics, SO2 poisoning mechanism and thermal regeneration capacity after SO2 poisoning of the CeWSnOx-800 catalyst were explored in detail by different characterization methods. We expect that this study can shed some light on the development of Ce-based catalysts for NOx removal from diesel exhaust possessing high thermal stability, catalytic activity and SO2 tolerance.