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

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。

Sulfur-poisoning and thermal reduction regeneration of holmium-modified Fe-Mn/TiO2 catalyst for low-temperature SCR

The effect of SO₂ on the low-temperature SCR activity and the thermal reductive regeneration for holmium-modified Fe-Mn/TiO₂ catalyst were investigated by activity assessment and various characterization methods. The deposition of ammonium sulfate ((NH₄)₂SO₄) on catalyst surface and the sulfuration of active component (MnSO₄) were proved to be the main causes for the deactivation in the presence of SO₂. The catalyst Fe_0.3Ho_0.1Mn_0.4/TiO₂ exhibited superior SO₂ durability when the concentration of SO₂ was lower than 0.04%, and the catalytic activity could markedly recover with the termination of sulfur-poisoning source. The deactivation behavior was irreversible when the concentration of SO₂ was increased to 0.1% but the deactivated catalyst could be regenerated after thermal reduction (350°C) for 60 min by 5% NH₃. The microstructure and physicochemical properties could be significantly restored after the thermal reductive regeneration. Moreover, the NO_x conversion could return to about 80%.