Improved NO reduction in the presence of SO2 by using Zr-promoted calcined NiAl hydrotalcite-like compounds and the regeneration of deactivated catalysts

The selective catalytic reduction of NO with propene (C3H6-SCR) was investigated over a series of Zr-promoted calcined NiAl hydrotalcite-like compounds. The obtained 5%ZrNiAlO catalyst exhibits superior NO conversion efficiency (93%) at 260 degrees C, and excellent sulfur-poisoning resistance. The possible reaction pathways of the catalytic process were proposed according to several characterization measurements. It is demonstrated that Zr-promoted NiAlO catalysts enhance the Bronsted acid sites and surface active oxygen groups and improve the redox ability. Meanwhile, the amount of the reaction intermediate is improved, as well as the reactivity of CxHyOz species with nitrite/nitrate species is promoted. Furthermore, in the presence of SO2, the ZrNiAlO samples can give rise to minor formation of sulfate and inhibite the competitive adsorption effectively due to their nitrite/nitrate species are more abundant and stable. In situ infrared characterization revealed the regeneration mechanism and water washing method showed best performance on the regeneration of S-poisoned catalysts.