The effects of calcination atmosphere on the catalytic performance of Ce-doped TiO2 catalysts for selective catalytic reduction of NO with NH3

Abstract

A series of well-reported Ce_x–Ti catalysts with a low content of Ce species were synthesized by a sol–gel method. The aim of this study was to investigate the influence of different calcination atmospheres on the formation of the Ce–O–Ti structure that comprises active sites for the selective catalytic reduction (SCR) of NO by NH₃. Catalytic activity tests showed that the Ce_x–Ti–N (calcined under a nitrogen atmosphere) catalysts exhibited a significantly higher NO removal efficiency than Ce_x–Ti–A (calcined under air). Characterization results confirmed that more Ce species could incorporate into the TiO₂ lattice when calcined under a nitrogen atmosphere, thus, more Ce–O–Ti structures were obtained over the Ce_x–Ti–N surface. This improved the NH₃ adsorption and electron transfer from Ti to Ce. Therefore, N₂ calcination increased the acid sites and improved the redox ability for Ce_x–Ti–N catalysts. In addition, it was found that the redox ability was the critical factor, which effectively promoted the low temperature SCR performance. Amongst the Ce_x–Ti–N catalysts, Ce₅–Ti–N revealed the best SCR activity, catalytic stability and resistance to H₂O and SO₂. This study demonstrated the feasibility of N₂ calcination in the syntheses of doped SCR catalysts and also explored the SCR reaction mechanism over the well-reported Ce_x–Ti catalysts. We expect that this study could shed some light on the development of feasible preparative routes for the syntheses of Metal-Ti catalysts for SCR application.