Ho改性Fe-Mn/TiO_2低温SCR脱硝催化剂硫中毒及热还原再生研究

Sulfur-poisoning and thermal reduction regeneration of holmium-modified Fe-Mn/TiO_2 catalyst for low -temperature SCR

以Ho改性Fe-Mn/TiO_2低温SCR脱硝催化剂为研究对象,通过活性评价和一系列表征技术对其低温抗硫性能和催化剂的热还原再生进行研究。结果表明,硫酸铵((NH_4)_2SO_4)在催化剂表面的沉积以及活性组分硫酸化(MnSO_4)是催化剂硫中毒的主要原因。当烟气中的SO_2体积分数低于0.04%时,Fe_(0.3)Ho_(0.1)Mn_(0.4)/TiO_2催化剂呈现出良好的抗硫性。在此条件下,当切断SO_2的供应时催化剂的脱硝活性可获得显著恢复。当通入的SO_2体积分数增加至0.1%时,催化剂会发生不可逆失活。在体积分数5%NH_3气氛下,失活催化剂经过350℃的热还原再生处理60 min后,其微观结构和理化性质能够得到明显恢复,且NO_x转化率可以回升至80%左右。

The effect of S02on the low-temperature SCR activity and the thermal reduction regeneration for holmium-modified Fe-Mn/Ti02catalyst were investigated by activity assessment and various characterization methods.The deposition of ammonium sulfate((NH4)2S04)on catalyst surface and the sulfuration of active component(MnS04)were proved to be the main causes for the deactivation in the presence of S02.The catalyst Fe03Ho0.1Mn0.4/Ti02exhibited superior S02durability when the concentration of S02was lower than0.04%,and the catalytic activity could markedly recover with the termination of sulfur-poisoning source.The deactivation behavior was irreversible when the concentration of S02was increased to0.1%but the poisoned catalyst could be regenerated after thermal reduction(350°C)for60min by5%NH3.The microstructure and physicochemical properties could be significantly restored after the thermal reduction regeneration.Moreover,the NOx conversion could return to about80%.