Al-PILC负载铜铁复合氧化物在NH_3选择性催化还原NO中的协同作用

以铝柱撑黏土(Al-PILC)为载体采用旋蒸-浸渍法制备了铜、铁单组分催化剂(Cu/Al-PILC、Fe/Al-PILC)和铜铁复合氧化物催化剂(CuFe/Al-PILC),并测试其对NH3选择性催化还原NO反应(NH3-SCR)的催化性能。相比Cu/Al-PILC和Fe/Al-PILC,CuFe/Al-PILC活性组分之间有较强的协同效应,显著提高了催化剂的脱硝性能。CuFe/Al-PILC在290~450℃的宽温区NO脱除效率保持90%以上,最高可达97%。此外,CuFe/Al-PILC有很好的抗水抗硫性能,催化活性不受反应气氛中水蒸气和SO2的影响。XRD、UV-vis、XPS和N2吸附脱附表征结果表明,CuFe/Al-PILC中活性组分相互作用生成CuFe2O4,有利于活性组分在载体表面分散,提高催化剂的比表面积和孔容;H2-TPR表征结果表明,CuFe/Al-PILC活性组分在载体表面生成的CuFe2O4改善了催化剂氧化还原性能,有利于NH3对NO选择性的还原;NH3-TPD表征结果表明,CuFe/Al-PILC在较宽温区范围内对NH3都有很好的吸附,这有利于提高催化剂表面还原物种的浓度,从而保证催化剂在较宽温区范围内具有较好的NO脱除效率。

Synergetic effect of Cu-Fe composite oxides supported on Al-PILC for SCR of NO with NH3

Cu/Al-PILC, Fe/Al-PILC and CuFe/Al-PILC were prepared by rotary evaporation-impregnation method using Al-PILC as support. Selected catalytic reduction of NO with NH₃ (NH₃-SCR) was carried out in a fixed bed reactor to evaluate their catalytic performance. Compared to Cu/Al-PILC and Fe/Al-PILC, CuFe/Al-PILC showed better NO removal efficiency (97%) and a wider temperature range (290~450℃) of 90% DeNO because of the strong synergetic effect of Cu-Fe composite oxides. Moreover, CuFe/Al-PILC showed good resistance to water vapor and SO₂. XRD, UV-vis, XPS and N₂ adsorption were used to characterize the structure of the catalysts. A new phase CuFe₂O₄ formed in CuFe/Al-PILC, which changed the surface properties of CuFe/Al-PILC, improved the dispersion of Cu and Fe on the Al-PILC surface and increased A_BET and v_p of CuFe/Al-PILC. H₂-TPR confirmed the existence of CuFe₂O₄, which improved the re-dox property of CuFe/Al-PILC. The result of NH₃-TPD implied that the surface acidity of CuFe/Al-PILC made it possible to adsorb and desorb NH₃ in a wide temperature range. The concentration of reducible species on the surface of CuFe/Al-PILC increased, which resulted in high NO removal efficiency.