水相法制备Ce-W@TiO_2催化剂的氨选择性催化还原NO(NH_3-SCR)活性和抗SO_2性能研究

采用水相法制备了Ce、W、Ti复合氧化物催化剂并用于氨选择性催化还原NO(NH_3-SCR)过程。TiO_2包裹型Ce-W@TiO_2催化剂表现出最佳的催化活性。205-515℃NO转化率超过90%。SO_2的存在造成所有催化剂低温段NO催化转化率的降低和高温段(425-540℃)NO催化转化率的升高,TiO_2@Ce-W表现出优越的低温抗SO_2性能。通过普通共沉淀法向Ce-W复合氧化物中引入Ti会导致催化剂表面W丰度、酸性位点的减少和低温NO转化率、耐SO_2性能的降低。通过水相法制备的TiO_2包裹型的Ce-W@TiO_2型催化剂,有利于表面W丰度、酸性位点、低温抗SO_2性能和催化活性的提高。

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.