铁铈复合催化剂的低温SCR脱硝性能

以柠檬酸酸法制备了不同铁铈比例的脱硝催化剂并将其用于NOx的低温NH3选择性催化还原，通过N2吸附、XRD和TPD手段对催化剂进行表征，并考察了H2O和SO2对催化剂性能的影响。结果表明：Ce的掺杂显著提高铁基催化剂的低温SCR性能，0.10CeFeOx催化剂在200~300 ℃，60 000 h-1空速下能达到85%以上的效率；Ce的掺杂能够提高催化剂比表面积和改善催化剂孔结构，有助于反应气体吸附以及提供更多的活性位点；铁铈之间有较强的相互作用，掺杂Ce后，Fe、Ce以无定型态存在，形成良好固溶体，并且大幅提高了催化剂表面酸性强度；在250 ℃，由于5%（vol）H2O竞争吸附导致0.10CeFeOx催化剂反应效率有所下降，但仍保持在90%左右；对于模拟烟气中SO2的毒化作用，250 ℃时0.10CeFeOx催化剂反应效率下降明显。

Low temperature selective catalytic reduction of NO with NH3 over CeFeOx catalyst

A series of cerium-iron mixed oxide catalysts were synthesized using the citric acid method and were investigated for use in the low temperature selective catalytic reduction (SCR) of NOx. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), and temperature programmed desorption (TPD) techniques. The H2O and SO2 durability of the catalyst was studied. The SCR of NOx at low temperatures was greatly improved by Ce-doping of the iron oxide catalyst. Indeed, mixed oxide catalysts with a Ce/(Fe+Ce) molar ratio of 0.10 yielded >85% NOx conversion between 200 and 300 ℃at a space velocity of 60 000 h-1. Greater specific areas and improved pore structures were obtained upon Ce-doping of the iron oxide catalyst, which contributed to the adsorption of reaction gases and provided additional active sites. In addition, a solid solution was formed due to the strong interactions between Fe and Ce. Furthermore, cerium doping significantly enhanced the surface acidity of the catalyst. Finally, due to competitive adsorption in the presence of 5 vol% H2O, the SCR activity of the 0.10 CeFeOx catalyst declined slightly, reaching a constant value of 90% at 250 ℃. However, due to deactivation by SO2, the SCR activity decreased significantly at 250 ℃.