Cd对V-Mo/Ti脱硝催化剂性能的影响

Effect of Cadmium on the Catalytic Performance of V-Mo/Ti De-NO_(x) Catalyst

为明确燃煤烟气飞灰中Cd元素对V-Mo/Ti脱硝催化剂性能的影响,采用浸渍法,制备V-Mo-Cd/Ti催化剂。采用X射线衍射(XRD)、N_(2)-吸附脱附、H_(2)-程序升温还原(TPR)、X射线光电子能谱(XPS)和NH_(3)-程度升温脱附(TPD)等手段,研究了Cd对催化剂物理化学性能的影响。同时,在固定床微型反应器上考察了不同催化剂的脱硝性能。结果表明:Cd会降低催化剂的比表面积。相比V-Mo/Ti催化剂,V-Mo-Cd/Ti催化剂上的V^(5+)物种减少,V^(5+)/(V^(3+)+V^(4+)+V^(5+))比率降低。此外,Cd还会造成催化剂的O_(α)/(O_(α)+O_(β))比率和表面酸量的降低。因此,V-Mo-Cd/Ti催化剂的脱硝活性低于V-Mo/Ti催化剂。通过将V-Mo/Ti催化剂中MoO_(3)的质量分数由3%提升至5%,可以有效减小Cd对催化剂的负面影响。

V-Mo-Cd/Ti De-NO_(x) catalysts with different content of Cd were prepared by impregnation method, aiming to investigate the effect of cadmium in the flue gas on the catalytic performance of V-Mo/Ti catalyst. XRD, N_(2)-adsorption, H_(2)-TPR, XPS, and NH_(3)-TPD analyses were carried out to characterize the catalysts. The catalytic activities of the catalysts were tested by using a fix-bed micro-reactor. The results showed that the presence of Cd could lead to the decrease of specific surface area of V-Mo/Ti catalyst. In comparison with V-Mo/Ti catalyst, the content of V^(5+)species of V-Mo-Cd/Ti catalyst was relatively lower, leading to the decrease of V^(5+)/(V^(3+)+V^(4+)+V^(5+)) ratio. Besides, Cd could also decrease the O_(α)/(O_(α)+O_(β)) ratio and acid sites of the catalyst. Consequently, the catalytic activity of V-Mo-Cd/Ti catalyst was lower than that of V-Mo/Ti catalyst. The negative effect of cadmium on the catalytic performance of V-Mo/Ti catalyst could be inhibited by increasing the MoO_(3)amount from 3% to 5%.