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

Abstract

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°C. The presence of SO2 leads to a decrease of low-temperature NO catalytic conversion and an increase of NO conversion above 425°C 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.