V2O5/赤铁矿催化剂结构及其NH3选择性催化还原NOx性能

以水热合成针铁矿为前驱体浸渍偏钒酸铵，分别于300，400和500℃空气中焙烧，制备了不同活性组分负载量的V₂O₅/赤铁矿（V/H）催化剂，用于氨选择性催化还原（SCR）脱硝。采用X射线衍射、透射电子显微镜、比表面积分析仪、程序升温还原及程序升温脱附等方法对催化剂结构进行了表征，并用标气配制模拟烟气进行了脱硝实验。结果表明，300℃煅烧3%V/H催化剂当烟气温度为250-300℃时NO转化率均可达95%以上；当配气中单独加入水蒸气或低浓度SO₂（0.01%）时，V/H催化脱硝的活性不受影响；当系统加入高浓度的SO₂（0.03%与0.05%）或同时添加H₂O与SO₂时，SCR脱硝效率下降，其机制可能是SO₂在催化剂表面竞争吸附所致，停止添加后，催化活性迅速恢复。

V2O5/hematite catalyst for low temperature selective catalytic reduction of NOx with NH3

A series of V₂O₅/hematite (V/H) catalysts were prepared by impregnation of goethite with NH₄VO₃ solution and used in the selective catalytic reduction (SCR) of NO with NH₃. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption, H₂ temperature-programmed reduction, and NH₃ temperature-programmed desorption. The effects of V₂O₅ loading and calcination temperature on the SCR activity were investigated. The NO conversion over 3% V/H catalysts calcined at 300℃ exceeded 95% at 250-300℃. Neither H₂O nor SO₂ (0.01%) had any adverse impact on the activity, but a decrease of SCR activity was observed after high concentrations (0.03% and 0.05%) of SO₂ were introduced. Cutting off the SO₂ supply resulted in activity restoration. The simultaneous addition of 5% H₂O and 0.03% SO₂ led to a synergistic poisoning effect, but when these gases were switched off, the activity was recovered. SO₂ adsorption on the catalyst surface led to the decrease in SCR activity.