燃煤烟气中碱金属化合物对V_2O_5/AC催化剂低温脱硝的影响:NH_3的吸附与氧化

Effect of potassium compounds on the catalytic activity of V_2O_5/AC for SCR of NO by NH_3 at low temperatures:NH_3 adsorption and oxidation

采用湿法浸渍-再干燥法将K2O和K2SO4担载到低温SCR催化剂V1/AC上,模拟研究了烟气中超细碱金属颗粒物对V1/AC催化剂脱硝活性的影响。结果表明,两种含K化合物的引入均导致了该催化剂的失活,明显抑制了NH3在催化剂上的吸附,尤其是热稳定性较低的吸附;K2SO4的抑制作用明显小于K2O,这与它们对催化剂SCR活性的影响规律相一致。K2O的担载对催化剂表面的氧化性能影响较小,但由于其能抑制NH3的吸附而引起催化剂的失活;K2SO4的担载则增加了催化剂表面吸附态的NH3在O2气氛中被过度氧化为NO的可能性。

K2O and K2 SO4 are loaded on the catalyst V2O5 （1% ）/AC （V1/AC） by the method of wet immersing followed by drying. The effect of potassium compounds on the catalytic performance of V1/AC for the low temperature SCR of NO by NH3 was investigated. It was found that both K2O and K2SO4 as ultra-fine particles loaded in V1/AC can cause the catalyst deactivation. The adsorption of NH3 on the catalyst, especially the portion of weakly adsorbed NH3, is inhibited remarkably by the loading of potassium compounds. The inhibition by K/SO4 is moderate, as compared with that by K2 O; this is also in accordance with the extent of their effects on the catalytic activity. K2O brings on little change in the surface oxidizability of V1/AC, the catalyst deactivation by K2O is a result of the inhibition of NH3 adsorption. Comparatively, the loading of K2SO4 may enhance the possibility for the adsorbed NH3 being oxidized to NO by O2.