Lean NOx Removal by a Bifunctional (EtOH + NH3) Mixture Dedicated to (Ag/Al2O3 + NH3-SCR) Dual-Bed Catalytic System: Comparison Between WO3/CeZrO2 and Cu–FER as NH3-SCR Catalyst

In a previous study, a drastic enhancement of the NOx conversion in EtOH-SCR process was achieved by means of ammonia and ethanol co-feeding over Ag/Al 2 O 3 catalyst to avoid the NO 2 /NOx ratio dependency of conventional implemented urea-SCR technology. The ammonia activation was mainly attributed to the availability of hydrogen H* species resulting from EtOH dehydrogenation, which promoted the H 2 assisted NH 3 -SCR over Ag/Al 2 O 3 . Additional conversion gain was reached with a dual-bed configuration in which a NH 3 -SCR catalyst (WO 3 /Ce x Zr 1−x O 2 ) was added downstream to the silver-based sample (Ag/Al 2 O 3 + NH 3 -SCR catalyst). This study deals with the influence of the SCR catalyst formulation on the catalytic performances of the dual-bed system. Oxide-based sample (WO 3 /Ce x Zr 1−x O 2 ) and exchanged copper zeolite (Cu 2.5 –FER) were selected as model NH 3 -SCR catalysts. Results shows that WO 3 /Ce x Zr 1−x O 2 in more appropriate in dual-bed configuration for (EtOH + NH 3 )-SCR process because ammonia and ethanol (or its by-products) strongly interacted together on Cu 2.5 –FER.