Probing NH₃-SCR catalytic activity and SO₂ resistance over aqueous-phase synthesized Ce-W@TiO₂ catalyst

A series of mixed Ce, W and Ti oxides catalysts have been prepared and employed to selective catalytic reduction of NO with ammonia (NH₃-SCR).It was found that Ce-W@TiO₂ exhibited the optimal catalytic activity.Over 90% of NO conversion could be obtained by the surface TiO₂-coated Ce-W@TiO₂ catalyst at 205-515℃.The presence of SO₂ leads to a decrease of low-temperature NO catalytic conversion and an increase of NO conversion above 425℃ over various catalysts, while Ce-W@TiO₂ exhibits the optimal low-temperature SO₂ resistance.It is noted that introducing Ti into Ce-W mixed oxide via the conventional co-precipitation method attributed to the decrease of surface W atomic abundance and acidic sites as well as inferior low-temperature NO conversion and SO₂ resistance.In contrast, the surface TiO₂-coated Ce-W@TiO₂ catalyst prepared via a modified aqueous-phase method exhibit increased surface W atomic abundance and acidic sites as well as the superior low-temperature NO conversion and SO₂ resistance.