Promotional effect of Al 2 O 3 on WO 3 /CeO 2 -ZrO 2 monolithic catalyst for selective catalytic reduction of nitrogen oxides with ammonia after hydrothermal aging treatment

Hydrothermal stability of catalysts for selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) has always been recognized as a challenge in development of candidate catalysts for applications in diesel engine emissions. In this study, Al 2 O 3 was introduced into CeO 2 -ZrO 2 to improve the NH 3 -SCR activity of WO 3 /CeO 2 -ZrO 2 after hydrothermal aging (HA) treatment at 800 °C for 12 h. The activity results indicated that the NH 3 -SCR activity of WO 3 /CeO 2 -ZrO 2 -HA was obviously improved in the whole reaction temperature range after doping Al 2 O 3 into CeO 2 -ZrO 2 , for example, the average and maximum NO x conversion were separately increased by ca. 20% and 25% after HA treatment. XRD, Raman, TEM and EDX results revealed that the introduction of Al 2 O 3 inhibited the sintering and agglomeration of CeO 2 -ZrO 2 and WO 3 and the formation of Ce 2 (WO 4 ) 3 after HA treatment. Accordingly, WO 3 /CeO 2 -ZrO 2 -Al 2 O 3 -HA showed remarkably improved structural stability and reducibility, increased surface acidity, and facilitated the reactivity between adsorbed NH 3 and nitrate species, which together contributed to its better catalytic performance after hydrothermal aging treatment.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology