镍改性ZSM-5催化剂及其SCR催化性能

Ni Modified ZSM-5 Catalysts and the Properties of Selective Catalytic Reduction

采用液态离子交换法制备了不同负载量的镍改性ZSM-5分子筛催化剂,并考察了上述催化剂的微观结构和物理化学特性及其在NH3-SCR反应中的催化性能。结果表明:在负载量<10.9%时镍在分子筛中具有高度的分散性,而随着镍负载量的进一步增加,分子筛表面开始出现较大的NiO颗粒;镍元素只以+2价存在于分子筛催化剂中;在NH_3-SCR反应中,镍负载量低于14.9%时,增加镍负载量将提高催化剂的低温活性;当反应温度超过300℃时,高温催化中心开始起作用,但随镍负载量的增加,高温活性开始下降时的温度逐渐降低。

Ni modified ZSM-5 zeolite catalysts with different nickel content were prepared using liquid ion-exchange method.The effects of nickel loading ratios on microstructure,physical-chemical characterization and selective catalytic reduction of NO_x with ammonia were investigated.The results showed that nickel species were finely dispersed on the ZSM-5 support with nickel content≤10.9%,the NiO particles began to appear on the surface of the zeolite catalysts with nickel loading ratio increasing;all of the nickel species in the zeolite catalyst is Ni～（＋2）;when the nickel loading was less than 14.9%,the activity of the catalysts at low temperature would increase with the nickel loading increasing in the NH3-SCR reaction;when the reaction temperature exceeded 300°C,high temperature catalytic center was activated,but with the continued increase of nickel loading,the temperature of high-temperature activity began to decline gradually reduced.